Isaac and Miria freaked out a little bit when they figured it out seventy years later, but adjusted quickly and had a great time, for example, being Dollars.
The last episode in the series is subtitled "Both the Immortals and Those Who Aren't Sing the Praises of Life Equally."
Tenzen Yakushiji from Basilisk has a parasite living inside his body that grants him immortality (though he's not completely immortal) and is shown to greatly enjoy it, even going so far as to gloat about it towards opponents who thought they killed him.
Tenchi Muyo! is made of this trope. The message essentially being: Immortality is great as long as you have a family of other immortals to spend it with, and you all really like each other.
In Gurren Lagann, Lordgenome spends his endless life raising kids, spawning beasts, suppressing revolts and has fun doing all three. Viral is made immortal by him and gloats about it to Simon.
Trigun leading man Vash doesn't age, and while he has a lot of angst none of it stems from this fact. He's a happy and goofy guy when his brother's not giving him grief.
Brought up by Kurt Godel. While everyone else is busy being all depressed about how someone immortal will outlive everyone they know, the idea simply thrills him instead. No need to worry about assassination, the ability to maintain an iron grip on the world for as long as you like... However, he was in the minority opinion on that one.
Evangeline sure seems pleased with her immortality, though it's implied that when she was younger that wasn't the case. If anything, she probably wishes she could still be immortal but with a body that was ten years older.
All of the robots that want to eat Casshern are this trope. They're pissed because they were enjoying immortality and now they can't because of the Ruin.
The other robots follow rumors of Luna's revival in the hopes that she can make them live forever too.
Luna herself enjoys eternity and is determined to make every robot in her presence share in it if they want.
Casshern himself reconstructs the trope. After seeing Luna's subjects laying about doing nothing with their eternal lives and how the robots he met on his journey did everything they could to find meaning in their brief lives, he decides to become the local Grim Reaper to prevent them from forgetting about death, and therefore, doing something with their time.
Soul Eater: Free was imprisoned and restrained for a long time with the knowledge that not even death could free him. It was so long he doesn't remember his own name. Does that bother him? No. The first time Soul impaled him, he bragged about it.
Code Geass: C.C. was originally the other trope but after the Grand Finale no longer feels this way, because Lelouch never hated or blamed her for the tragedy that his life became, and through everything he honestly cared about her, allowing her to live out her immortal lifespan with the happy memories he gave her.
Shakugan no Shana: Considering that it replenishes his Power of Existence every night, Yuuji wonders if the Reiji Maigo will make him live forever. If this is the case he considers it a good thing because it means he can stay with Shana forever.
Magician's Academy: Immortality means you have all the time in the world to study moe and collect rare items like limited edition capsule toys.
Highlander: The Search for Vengeance: Marcus pines for Rome but, unlike Colin, he looks to the future because he believes he can recreate it through conquest. He knows things die, but you move on and helped build civilzations.
The elves and trolls in ElfQuest may count, since they're all either immortal or very long-lived. None of them ever seems to complain about life getting boring (some of them are too busy trying not to get killed anyway), except the Glider elves who are bored and decadent. Some of the elves do strike up bittersweet friendships with short-lived humans, though.
Notably, the bored Gliders are the oldest living elves, except for Timmain, who spent millenia in wolf form. As a wolf, she could not note the passage of time, giving her immunity to this effect.
Morpheus makes a deal with Hob Gadling: he doesn't die, but they meet every hundred years in the same tavern. After two hundred years, Hob tells Morpheus how he got rich, married, and had a son. Next time, he's poor, his son died young, he can't remember his wife's name or face, he generally looks the picture of misery, the kind of guy the Pope would gladly Mercy Kill. Morpheus asks if Hob wants to die... to which Hob smiles and says "Of course not". Centuries later, when Death comes to see Hob to tell him Dream is dead and asks if he wants to die, he still says no. Hob seems to ultimately manage because he accepts that life has both ups and downs so there's no point in despairing completely during the bad parts or expecting the good times to last forever.
Mad Hettie is determined to keep on going no matter what it takes, even though she's mad. It's unclear whether she was mad to begin with or whether immortality made her so.
The Brief Lives storyline features Bernie Capax, a dull, unassuming lawyer who dreams of the mammoths he once walked among. He's usually a lawyer; people always need lawyers. He's quite surprised to hear himself scream "NOT YET!" when he's killed in a freak accident.
The Eternal Flame from Troy Hickman's Common Grounds was the man to whom Prometheus gave fire to. It gave him power over fire and immortality. He becomes a superhero and is still able to enjoy his immortal life.
The Archons in The Secret History may go through a lot of shit, but hey, they still more or less control world events and Reka gets to bed famous men throughout history.
Vandal Savage occasionally has bouts of weariness concerning his existence, but for the most part he really gets a kick out of being an evil immortal bastard. He's got an entire world he hasn't conquered yet and enemies that are still alive after all. Most telling is that Vandal could end his immortality by refraining from eating his descendants' flesh and organs but he doesn't.
Averted for the most part in Fables, with the notable exception of Pinocchio, but only because he's stuck as a permanent pre-adolescent and wants to age so he can grow up. Thus it's not 'living forever is bad' but 'living forever as a child is bad'.
X-Men: Cameron Hodge is a dark version of this trope. He founded an anti-mutant organization targeting Warren Worthington, aka Angel, and his current team, X-Factor. As part of his preparations, Hodge made a deal with the demon N'Asrith for immortality. Unfortunately by that point Angel had become Archangel and he cut Hodge's head off in short order. As per the deal, Hodge survived... as a disembodied head. Hodge returned later with a cyborg body during the X-Tinction Agenda, only to end up as a disembodied head buried under a mountain of rubble. He returned a third time as part of the techno-organic Phalanx, at which point the authors had forgotten about his immortality and supposedly killed him off, only for him to return again and finally get Killed Off for Real (maybe) during the Second Coming crossover. While he suffers many pitfalls of immortality, he never laments his condition - instead he throws it back in the X-Men's faces. He's so insane with hatred that being a buried head is worth it if he can hurt just one mutant.
In Marvel Comics, the Elders of the Universe relish immortality since it lets them pursue their personal obsessions forever. Then again, they are insane.
This is also true of Eternals and most gods (especially Hercules). However, since most of them live in a Society of Immortals and their closest friends and relatives are immortal too, they only have to feel badly about their mortal relationships.
Mercury-2: "Not really. I know, you're worrying if after a thousand years a person starts getting bored with life?"
Ami: "That was one thought…"
Mercury-2: "It's sour grapes. Think about it: every single day, all over the Galaxy, something new is happening. Something new to see or do or learn or talk to. A thousand years hasn't been nearly enough."
Ami: "…But… do you ever get tired of each other?"
Mercury-2: "Well, everyone has disagreements now and then. Mars and I once spent fifteen years… well. My fault, really. But… You know how good it feels to fall in love… and how much better it gets after you've been together for a while?"
Mercury-2: "It's a linear progression. Add a thousand years."
Mercury-2: "You're just starting a very long and wonderful journey. Trust me: you won't regret it."
The Pirates of the Caribbean fanfic Jack To The Future postulates that Captain Sparrow successfully located and used the Fountain of Youth, achieved Type II immortality, and spent the next few centuries participating in various historical events. This includes both positive and negative experiences, but overall he seems to be having a good time.
Harry Potter and the Methods of Rationality have Harry himself take this stance (and give a long list of the things he would do with his time to Dumbledore, in answer to his Who Wants to Live Forever? position), not only for himself, but for everybody on Earth. He even dreams of the very idea of death becoming nothing more than a grim story that future children aren't told until they're old enough to take it.
It's the whole point of its spinoff Luminosity as well.
The Great Alicorn Hunt seems to be a backlash against all the MLP: FIM fics about the opposite trope. Yes, Princess Celestia and Luna are tired of outliving everypony else (besides each other), but everything else about immortality is great so they're trying to end mortality for everypony.
Discussed in The Petriculture Cycle. Twilight doesn't want to use her newfound powers to solve the story's conflict because using them would make her live forever. Penumbra, an immortal, talks her into it by, among other things, refers to a saying common among alicorns: "Mortals pass away eventually, but an immortal doesn't leave until they're ready to go."
In the Pokémon fanfic Brave New World'', anyone that joins Deoxys' crew is offered immortality. Even after traveling to the far reaches of the Omniverse and living for millennia they still enjoy it.
Giovanni and Mickey have lived since the Catacylsm a thousand years ago. Neither of them have any complaints.
Leo has been gifted with Resurrective Immortality and Darkrai has explicitly told him how to become fully immortal. He even admires Leo's work on the iron-clad immortality contract he drew up. So help us, Arceus...
In the Death Note fanfic Low Light, Light and L are (for reasons yet unknown) favored by the Shinigami King who makes it so that they cannot be killed (at least by the Notebook). They’re loving it so far.
In the Hellsing fanfic series Worse Than Death Series, though they don't outright say the trope word for word, none of the good characters angst over being immortal. Probably because there's so goddamn many of them that they don't need to angst over leaving people behind, and they won't have to move about since they're tied to one organization.
In The Man from Earth, the immortal John Oldman makes the best of eternity, gathering huge amounts of knowledge over the centuries.
Some immortals - namely the good guys - are shown balancing the loneliness of immortality by enjoying life to the fullest and using their immortality to develop new pastimes and experience the world like no humans can. For example, Methos - the oldest immortal - has written a journal chronicling most of his life and experiences (at least some of it -he is older than writing, so some stuff went undocumented). The episode "Stone of Scone" shows this very well.
R2-D2 has survived the entire series and according to the Star Wars Expanded Universe is still alive to this day. Unlike most droids, who have regular memory wipes, Artoo has never had one in its entire 200 or so years (and counting) of existence.
Luke similarly comments in the Expanded Universe on what it means if his powers make him immortal. The secret is that Jedi are immortal; it just takes compassion to make them so.
Ultimately his descendant Cade does have the power to raise the dead.
Casca, the eponymous mercenary of Casca: The Eternal Mercenary, is rather satisfied with his immortality as a whole although he has his occasional moments of regretting it when stuck in a Fate Worse than Death like being buried alive for decades.
Groundhog Day plays with this trope. The main character goes back and forth between enjoying and despairing over his situation. But it's a bit different from standard immortality since he's living the same day over and over which obviously has different advantages and drawbacks. He begins with hedonistic excess, then falls into despair as nothing he does means anything, then finally finds peace in deciding to be the best version of himself he can.
Jack Sparrow wonders whether immortality as the captain of the Flying Dutchman, which would mean only getting to visit land for one day every ten years at sea, is this or Who Wants to Live Forever?. Hilariously he uses rum as his criterion and tries to figure out whether a mortal lifetime with an unlimited access to rum means more or less rum than an immortal existence with access to rum once every ten years. Ultimately, all the opportunities Jack has come across that could render him immortal have come at too high a price for him to accept. If he could find one that didn't require a Human Sacrifice or some other kind of undesirable commitment, he'd probably go for it.
Davy Jones himself certainly enjoys his eternal dominion over the ocean and he sells this idea (or, more appropriately, that death is worse) to new recruits. One can presume he originally took up his post on the Flying Dutchman hoping for Eternal Love with Calypso.
Hancock: Hancock and Mary decide to split permanently because they enjoy their immortality. Hancock, for instance, wants to be a super hero forever.
Invoking this trope is one of the Duumvirate's stated goals. They refer to it as "going to the future". Their rejuvenated fifty-year-old creator strongly agrees.
Several of the Old Gods in American Gods seem to still enjoy their eternal life immensely, despite their lack of worshipers cutting their powers down to the barely-superhuman level. Most notably, of course, is Anansi, who is always enjoying life, even on those occasions when he's (temporarily) dead.
For the most part, the sorcerers of the Belgariad seem perfectly content with eternal life. This is in part because they keep very, very busy. (One, Senji, doesn't even notice he's immortal until he takes a break from trying to turn lead into gold and realizes several centuries have passed.) Not all of them were so content. Of course, those ones are not around anymore.
And those who hated their life usually had another reason than immortality to hate it. For one, it was the horrors of war.
Peter Pan milks every bit of fun out of eternal youth. It helps that his memory spans an average of five minutes.
Bella finds no qualms at all to be spending all eternity with her teenage husband, super-quick aging daughter, and her beautiful and wealthy extended family.
Likewise, the members of the Quileute tribe that are blessed with spirit wolves rapidly age to probably about their early twenties and then stop aging until they choose to willingly give up their ability to transform by remaining human for a certain amount of time. Jacob is lucky enough to have imprinted on the half-vampire Renesmee, who likewise ages rapidly before abruptly stopping somewhere around age 16. While the future is never confirmed, it can be assumed that Jacob probably opted to keep his wolf form for as long as possible.
Tarzan and a few of his friends attain eternal life and youth by stealing some immortality pills from one novel's Big Bad (he cannot share immortality with the world, due to the pill's morally dubious manufacturing method). Tarzan has a very upbeat, "seize the day" mindset and is completely unbothered by the consequences of his immortality. When asked by someone if the thought of all his friends growing old and dying bothers him, he replies that the promise of making new friends makes up for it. When asked if he is worried about boredom, Tarzan replies that he lives such an exciting life, he doesn't worry about it.
In Aleksandr Zarevin's Lonely Gods of the Universe, not one person (either human or Ollan) who has become immortal after eating Ambrosia (it's a plant, not a drink) regrets being mortal. Yes, women become sterile (see Immortal Procreation Clause), but they don't really care. Men can still father children with mortals (and have). Their lives get even better after they eliminate monogamy among themselves (at the women's request) and just have giant orgies. They have a limited supply of Ambrosia and no way to get more, so they have to hand it out sparingly, but one full dose is enough to heal any injury (even regrow lost limbs) and restore youth, as well as grant eternal life. A partial dose will only do the first two.
Not quite living forever, but pretty much everyone agrees that Prolong, an anti-aging treatment in the Honor Harrington stories which extends the active human life to around three centuries, is pretty damn awesome. Amongst other things it lets you spend fifty or so years in a Naval career and still have over two centuries left to do other things if so desired.
In the Iron Druid Chronicles Atticus is more than two thousand years old and he is still enjoying his life enormously. It helps that he is an earth druid so he has a very close bond with nature which grounds him and preserves his sanity. The werewolves also seem to enjoy their long lives.
The Others in Night Watch almost never have regrets about their unnaturally long lives. However, most of them try to avoid having children so as not to have to watch them grow old and die. An Other's child can become an Other, but this has about as much chance of happening as an Other born from Muggles. The only exception are vampires and werewolves, who turn their children, but they are the lowest of the low in the Dark Other hierarchy.
Sergey Lukyanenko: in his short story "I'm in no hurry", a Genre Savvy student summons a devil and offers his soul in exchange for infinite wish fulfillment. As a side effect, a deal made him completely immune to age, harm and restrictions to action or communication, except for those caused by the wish itself. Decades later, the devil finally freaks out about his master (now a world-famous, wealthy scientist, still looking as he did in his prime) never making a single wish. The professor reveals that he feels pretty capable of achieving anything he wants on his own, and all he needed was an unlimited (and youthful, and And I Must Scream-free) time.
Fablehaven: There are 5 immortals who all function as Barrier Maidens. Two aren't identified and killed offscreen, Marcus is Who Wants to Live Forever?, Civia regards her immortal life as a duty which she always regards as important. Roon, though he died offscreen like the first two, was said to have enjoyed his immortality. He formed a hunting pack of the finest men to go and hunt various dangerous monsters, and was described as a Boisterous Bruiser. His body is found amidst the bodies of his attackers and allies; his familiar even suspects that he would have won the battle if not for the enemy having magic.
Adventure Hunters: Gargoyles live for a very long time, and since many of them are historians, they find this very helpful.
Malazan Book of the Fallen: Onrack is a T'lan Imass that's quite happy with his condition, as "there was always something else to see, after all."
Dirge for Prester John: Invoked. The Abir exists to change up people's lives every couple centuries to make sure no one is bored or dissatisfied with living forever.
The Misenchanted Sword zigzags this trope. The main character receives a sword which will not allow him to die until he has killed 100 men with it. He decides to live forever and not kill people, but this decision is based on morality instead of the merit of eternal life. Then he discovers that the sword lacks a Healing Factor and will not keep him young so he goes on a killing spree as an old man then he discovers magic that can keep him young and at the end of the story is quite happy with his situation.
Inheritance Cycle: This becomes a vague plot point in Brisingr, when Eragon realizes he has become immortal. Instead of angsting about it, he decides to look for a wife among the elves because they are all immortal. Good thing he's already head over heels for Arya.
There are three sources of immortality in Harry Potter but only The Elixir of Life lacks downsides. It will keep you alive with repeated doses, and has eternal youth (or at least eternal middle age) added in.
Tortall Universe: Part of the reason Faithful / Pounce keeps coming down to the mortal realms is because there's always more heroes to follow and snark at.
Journey to the West: There are no end to mortals who 'cultivated their conduct' and/or 'refined their spirit' to become immortal and love it. It's Truth in Television, sort of, as this was the goal of real life Taoists.
The Wuzhuang temple has a community of immortals because of a tree that produces life extending fruit and are extremely protective of it.
Son Wukong began his journey seeking to become immortal and only regretted it during that one time he was trapped under a mountain. He takes pride in calling everyone he meets "grandson" because of his great age.
Live Action TV
The Doctor in Doctor Who experiences a lot of heartbreak, but still feels that life is worth living so long as there's something left to see in the Universe. Also, the Face of Boe, to an extent.
In Torchwood, Captain Jack Harkness in general. Sure, he has ocasional angst over it, but considering his average deaths per episode count, he sure is getting his money's worth out of the deal. Also, more time to go hit on people.
Inverted in Torchwood: Miracle Day, where (almost) everyone on Earth becomes unable to die. Even suicide bombers are still alive, despite being charred beyond recognition. Also, while people stop dying, no one stops aging. Inversely, Jack loses his immortality and has the time of his (very long) life, although now he insists on using condoms.
The Middleman has Cecil Rogers, in the episode "The Cursed Tuba Contingency". He's been cursed to wander the earth unaging ever since he kicked some people out of a lifeboat on the Titanic, and says that, he thinks this is pretty neat.
A good number of Immortals in Highlander: The Series seem to be having a grand old time; sure, they have problems, but they still enjoy their lives. The protagonist is a major exception — but he'll still fight tooth and nail to survive. He only seems to regret being immortal when something really bad happens in his life.
In Can You Live Forever?, Adam's greatest regret after his first thousand years is that his children all died before his 132nd birthday. However, he loves to show off his collection of awards and spare bodies.
Buffy the Vampire Slayer: The greatest difference between Spike and Angel is that the former believes in this trope. He even vampirized his mother so that between her and Drusilla he'd never be lonely (it didn't work out, but that was thanks to the vampiric transformation).
There's a human turned robot in Stargate SG-1 who refers to this trope as "The Gift". For context, he is trapped in a facility that's constantly falling apart because if he left his body would run out of electricity within hours. He spends all his time fixing problems or checking for problems. All alone. Even after living this way for centuries he still considers immortality a good thing.
Dead Like Me: Played with. Unlike the other reapers who are angsty or apathetic, Mason's pretty happy with his lot in death. On the other hand he envies the souls that get to pass on while he has to stay behind, but this is because whatever's on the other side is better than the side he's on.
Star Trek: The Next Generation: The opinion of his race as a whole but Q in particular believes this trope. One of the most severe punishments they have (and sentenced Q to once) is to make one of their own mortal.
Agents of S.H.I.E.L.D.: Professor Randolph is a Asgardian warrior that retired on Earth. Now he teaches Norse Mythology. The Team estimates that he's been alive for a thousand years and his only complaint is a student putting too much Lit Crit and not enough History in their paper. He's had numerous paramours over the ages. He's also so patient that he's perfectly willing to wait for a human he doesn't like to die of old age.
In The Legend of Maian, most of the Regis Knights, immortal super warriors who can't die till their -also immortal-master dies.
I am immortal. I have inside me blood of kings. I have no rival. No man can be my equal. Take me to the future of your world!
The song "Immortal" by Clutch makes it sound pretty awesome:
Who's the man who stole fire for the people? Who causes trembling in the bones of evil? Who carved a mountain into a cathedral? I am immortal.
The backing lyrics for the chorus repeats the phrase "in dog years," suggesting the narrator isn't immortal—at least not literally.
The Brazilian song "Eu nasci ha 10000 atras" (I was born 10000 years ago) by Raul Seixas is (obviously) about a man born 10000 years ago who talks about famous events he witnessed. He sounds very enthusiastic about his life:
Eu nasci há dez mil anos atras... (I was born 10000 years ago) ...Eu vi Cristo ser crucificado... (I saw Christ crucified) ...Vi Babilônia ser riscada do mapa... (I saw Babylon be wiped off the map) ...Eu vi conde Dracula sugando sangue novo... (I saw Dracula drinking blood) ...Eu tava junto com os macacos na caverna...(I was with the monkeys on the cave) ...Eu vi a estrela de Davi brilhar no céu (I saw the Star of David shine in the sky)
The long-lived and nigh-immortal Eldar of Warhammer 40,000 fight tooth and nail to survive. Granted, it's not so much that Living Forever Is Awesome but rather that dying is much much worse. If Eldar are lucky they will have their souls trapped in crystals for all eternity. Otherwise, they become the playthings of the Chaos god Slaanesh.
This trope fits the Dark Eldar even more. They can achieve immortality by drinking the souls of lesser races (and by that, I mean anyone who isn't a Dark Eldar), and they get to live a life of fighting, torture, sex, drugs and cruelty, which is extremely fun to them. Of course, they're Eldar too, so there's also the Chaos god Slaanesh out to get their souls when they kick the bucket and can't be brought back.
Also fits Orks. They're like lobsters; they never die from old age, they just keep growing bigger and stronger until something kills them. The largest and oldest Orks are the size of Imperial Dreadnoughts and just as powerful, while also having lived for hundreds if not thousands of years and probably seen just as many battles. Of course, very few will actually reach that state due to the incredibly brutal and violent nature of their existences, although being Orks, they don't really mind.
The Mummies of the Old World of Darkness are generally of this opinion. They might live in a Crapsack World and have often difficult battles against terrifying foes but hey, they have literally all the time in the world to put things right and plenty to enjoy along the way.
In Dungeons & Dragons Liches, undead spellcasters, are generally of this opinion which isn't a big surprise since they become liches for this reason. It helps that they have a lot to occupy themselves with studying the deepest darkest arcane mysteries, or consolidating wealth and power for elaborate schemes that play out over centuries.
The Longevity Vaccine and Clinical Immortality projects from Sid Meier’s Alpha Centauri, The Longevity Vaccine will eliminate 1 to 2 Drones and/or boost your economy by 50% based on your economic model, and Clinical Immortality nets you a free Talent at every base plus 50% more votes in elections. It helps that these are presumably widely available treatments, meaning everyone lives forever and the worst aspect of Who Wants to Live Forever?, the losing people you love, is not a problem.
"I plan to live forever, of course, but barring that I'd settle for a couple thousand years. Even five hundred would be pretty nice."
— CEO Nwabudike Morgan, Morganlink 3D-Vision Interview
Interestingly, the novelizations claim that the treatments are only available to the higher-ups. This handwaves why the faction leaders are still alive after centuries of rule.
The guy who constructs the training courses in Immortal Defense seems to think this. Even as all the other path defenders go insane one by one and start leaping across the Moral Event Horizon. It helps that path defenders tend to go insane because they fixate on something and will go to any lengths to protect it; he ended up fixating on...constructing training courses.
Many characters in the Touhou series are happy with their immortality.
Yuyuko used her superpower of instant death to (somehow) permanently remove herself from the cycle of life and death, trapping her in the netherworld to seal a world-devouring evil spirit in a tree, and now lives quietly whenever she isn't causing trouble to sate her boredom. Although her canonical Crouching Moron, Hidden Badass nature makes it hard to tell for sure, she seems to generally enjoy her eternal un-life, especially when it comes to teasing her overly-earnest subordinate, Youmu.
Eiki and Komachi, respectively as judge of the dead and ferrywoman of the equivalent of the River Styx, never really seem to complain about "outliving" everyone they know, but then, being Anthropomorphic Personifications of death and rebirth, and the knowledge of how the afterlife works may give them a radically different perspective on the whole thing.
Kaguya and (probably) Eirin, seem to be enjoying immortality quite a bit. Kaguya seems to mostly suffer from boredom, but has had Eirin taking care of her essentially her whole life. She also has mortal, if extremely long-lived servants, but she seems not to care about them to the point of calling any and all of them "Inaba", rather than learning their names.
Fairies may have the most amusing of all immortalities — they are functionally immortal as long as the force of nature that they represent still exists. They, however, are all permanently child-like, and spend all eternity playing pranks on one another, don't bother with notions like owning any property they don't wear on their backs (if clothing doesn't just magically appear on them in the first place, it's not like they would manufacture all the frilly dresses they wear) not really understanding the difference between yesterday and ten thousand years ago.
To be specific, they have Type IV immortality: they simply regenerate after being killed.
We could've made this list so much shorter simply by stating that the only character who isn't of the opinion that immortality is awesome is Fujiwara no Mokou, who's lifestory goes something like this: Father got disgraced by above mentioned immortal Kaguya, Mokou drank the Hourai elixir to get a fair shot at Vengeance, got ostracised when people eventually noticed her unchanging appearance, became a hermit and lived alone for quite some time, went absolutely Ax-Crazy for two-hundred years and proceeded with killing anyone and anything that came in her way, went into a bit of a decline and lived in an apathetic depression for a few hundred years, finally found her way to Gensokyou where she found Kaguya again, re-ignited their rivalry and has since then spent the time locked in an eternal circle of revenge murders with her arch-enemy. It's not so very weird that she really regrets drinking that damn immortality potion, is it?
Soul Calibur - Zasalamel, who had previously been all about Who Wants to Live Forever?, gets to see a vision of mankind's far future in the fourth game and decides to keep his immortality instead of ending it to see the advance of mankind. We get a scene of him as a rich businessman with a helicopter in the 21st century in the end.
The basic premise behind the ending of Lost Odyssey. Kaim and two of the other good immortals settle contentedly into their immortal lives, reasoning that eternity isn't so bad after all. It helps that two of them are married to one another, and the third, although her husband is mortal, is a queen with a whole country to keep herself busy with throughout the centuries to come.
Radiata Stories: When Parsec the Fire Dragon asks Aphelion the Silver Dragon why he defends the humans, his reply is, in a nutshell, 'it's not fair that dragons and elves get to live forever when humans don't.' His ultimate goal involves extending his own immortal life.
In World of Warcraft the High Elves (by way of the Well of Eternity) and one of their descendent branches, the Night Elves (by way of the World Tree), were contentedly immortal for well over 10,000 years (not including the whole War of the Ancients thing). Many Night Elves were rather sad to lose their immortality due to the events of Warcraft 3, and though it was a necessary sacrifice World of Warcraft opens with the Night Elves trying to regain their immortality through the creation of a new World Tree (the attempt does not go as planned).
The Draenei appear to be functionally immortal (they do not seem to die of old age) and their leader, Valen is at least 100,000 years old. Immortality does not bother them at all.
Sylvanas Windrunner used to be all Who Wants to Live Forever?, but after getting a taste of The Nothing After Death all evil Undead are doomed to visit when their undeath ends, she's decided that an unending undead existence isn't that bad in comparison.
Glados's final song in the end of Portal 2 has a tinge of thatnote One day they woke me up/ So I could live forever/ It's such a shame the same/ will never happen to you, though many speculate that it hides her bitter hatred at her own existence and that she just sent the closest thing she had to a friend away.
Most of the Daedra, especially the Daedric Princes, of The Elder Scrolls series rather enjoy their immortality. A good example is Sanguine, who basically just lives to have fun. His quest in Skyrim could be described as an Elder Scrolls version of The Hangover or Dude, Where's My Car?.
Variation: Cucuvea the mystic believes she would have had this attitude... had she been able to spend her immortality anywhere other than Transylvania. Living in an extremely damp hole under a tree, obligated to defend the local villagers, and under constant threat from roaming vampires and werewolves, she's not exactly having a good time.
Forerunners of Halo wear armor that effectively stops aging, among other things. Aside from a few "naturalistic" ones, this applies to their entire society, so it's less "Living Forever is Awesome" and more "Living Forever is Normal". They are capable of dying, but this is exceedingly rare, aside from the lowest rates with dangerous jobs.
Suikoden: Every holder of a True Rune is immortal by default. The responses to this are mixed.
Geddoe carries True Lightening and while he's not a happy guy he's not angsty either and it comes in handy in his line of work.
Ted didn't like his rune, the Soul Eater, and at one point gave it up but then he took it back and lived for hundreds of years more. He only died because the villain of Suikoden I stole the rune from him.
Defied in Final Fantasy III. The three immortal students received the gift of magic, the gift of dream, and the gift of mortality. Mr. Mortality is PISSED but the other two and their master firmly believe the ability to die was a great gift.
Played with in Final Fantasy XIII-2. The Heart of Chaos makes Caius immortal but the endless life doesn't bother him. It's watching his charge, Yeul, die at a young age over and over again that drives him to madness and his Evil Plan. However, that plan involves merging the world of the living with the world of the dead so no one would die.
The Suul'ka in Sword of the Starsenslaved the rest of their fellow Liir so they could live forever in outer space. None of them feel any regret about this decision.
You know in those stories there's this immortal guy and they talk about how bored they are and how boring life is after 5000 years or whatever? I am going to call something. I am going to call SHENANIGANS.
The Kingfisher: Most of the vampires in this comic show no signs of boredom or guilt at the prospect of immortality. Dragomir vampires especially seem to enjoy eternal life.
Raven Wolf: is half this and half the other trope. The titular tribe was cursed by their totem spirits with "removal from the cycle of life" until the domestics (a faction of "civilized" furries) are no more. The usual angst about outliving one's loved ones is partially averted because anyone who marries into the tribe is cursed as well and their children inherit it, but if they fall in battle their souls are devoured by the wolf spirit.
The Gods Of Arr Kelaan - Claremont asks a fellow god for a favor to bless a potion destined for his daughter to give immortality upon consumption, to which is refused - death is a birthright to all humans - but Thanatria nuances it the right way. Whomever takes this potion will not die until they wish to.
ThisSaturday Morning Breakfast Cereal has a genie curse someone with immortality, and goes through the standard list of reasons for immortality to suck (stagnation, alienation, outliving loved ones), but the guy refutes all of them. Eventually the genie comes up with "You will have to watch continued remakes of beloved movies."
Not awesome per se, but the narrator of The People I Have Been from The Wanderers Library seems quite happy with his arrangement, saying “I've been a soldier and a minister, a leader of men and a follower of causes. I've preached hellfire and harmony. I've said words profane and holy. I've been people I didn't like, and people I wish I could be again. But that's life, Emma. Life isn't static, it isn't frozen. Life doesn't stand still. It changes, and it changes us. This is just another step.”
As the title suggests, Die Now or Live Forever has this trope Nobody wants to become a vampire, but once you are one, you enjoy it.
A feature of the afterlife in many religions such as Christianity, Judaism, Islam, and some forms of Buddhism like Pure Land.
The modern Transhumanists hold the opinion that if you do get bored eventually, then you are free to end your own existence, but why not try to see how long you last just in case that doesn't happen? Lots of interesting hypotheses have been made for escaping the universal heat-death, as well, although how well those would work in practice is anybody's guess. There're countless of billions of years to test them, so there's hardly any hurry.
Demona has lived for centuries and there's not a trace of weariness or boredom to be found. Macbeth, who became immortal at the same time, lives only to kill her so that he himself may die. Eventually, though, he finds something else to live for.
Batman Beyond: Ra's Al Ghoul loves immortality so much he's gone through three seperate methods of beating back the grim reaper.
In My Little Pony: Friendship Is Magic, living for well over a thousand years and having to make some particularly nasty choices along the way haven't dampened Princess Celestia's spirits at all. She still enjoys the simple things in life like hanging out at a doughnut shop with friends, playing harmless pranks, and cooing over her pet.