Watching Sora willingly jump off the plank of Captain Hooks ship in the first game because he believed he'd be able to fly was heartwarming enough. Moments later we get to see his faith rewarded as he soars away before the crocodile can eat him.
Watching Sora and Donald happily reunite thanks to Tarzan, sure it's quickly spoiled by a CMOF, but it's a sign of things to come.
"This boat runs on happy faces."
The conclusion to Sora's last visit to the Hundred Acre Woods in the first game has him, Pooh, and all their friends looking up at the big, beautiful moon together on a hill, before Sora waves goodbye, and the cover of the book changes to a drawing of Sora holding Pooh's hand as they walk side-by-side.
"Sora, don't forget. We shall always be here. If you'd like to visit again, that is."
Kairi bringing Sora back from the darkness and transforming him from a heartless back into his normal state by hugging him.
Sora: Kairi... thank you.
Not to mention Donald and Goofy's happy reaction upon seeing Sora turned back to normal.