Just before or after doing something extremely risky and difficult, the seemingly calm and stoic character suddenly pauses and takes a few deliberate, audible breaths before proceeding. What happened is that in-universe, the character used hyperventilation to relax tense muscles and improve their performance. Out-of-universe, the writer used a simple shorthand to demonstrate how stressed and Not So Stoic that character is (or was, if it happens afterwards) without telling it explicitly.
Compare Hyperventilation Bag. Can be used to avoid a Rage Breaking Point. Take a Moment to Catch Your Death is a horror genre variation where this segues into a Death Trope. See also Cathartic Exhalation for when the air is let out of the lungs after a stressful event.
- Done by, of all characters, B.E.N. in Disney's Treasure Planet, who is actually a robot, and doesn't need to breathe. B.E.N. does so anyway after killing all the lights aboard the Legacy while attempting to disable the on-board weapons systems. Of course, in his case, anything that might avert another monumental screw-up is worth a try.
- Astronaut Dave Bowman does a lot of measured breathing in 2001: A Space Odyssey while he's working to disable the homicidal HAL-9000 computer. If Bowman disables too few circuits, HAL might succeed in killing him nonetheless; if Bowman disables too many circuits, the spacecraft Discovery will become unmanageable to the point of being a deathtrap.
- Avengers: Infinity War: Before attacking the Big Bad Thanos, Loki appears to be calm and collected, but then takes a deep breath specifically to show how frightened he really is.
- Subverted in Artemis Fowl: When Mulch is in a prisoner shuttle transferring him to the Atlantis prison, he starts taking deep breaths, which his guard assumes to be a normal behavior due to stress. However, Mulch is actually compressing vast amounts of air in his gut to the point where the submarine actually starts crumpling in on itself. The guard barely makes it to the cockpit/escape pod while Mulch makes his high-speed escape leaving only a trail of malodorant bubbles.
- In Ace Combat: Assault Horizon, when the resident Stoic Doug Robinson flies off on a solo mission over the enemy territory with no backup and a lot of lives at stake, he takes several deep, deliberate breaths as the mission starts — the first indication that the stress is getting to him, too. However, he manages to control himself and complete his mission just fine after that.
- Fen Quest: When Fen and Aira question Sir Zall's identity in the face of orders that contradict his previous ones (also they've never seen him angry before), Zall "lets out some noise that I'm not sure is a sigh, a deep breath, or a hiss" as he collects himself before amending his orders to comply with their paranoia.
- In the My Little Pony: Friendship Is Magic episode "Games Ponies Play", Princess Cadance teaches Twilight a deep-breathing technique to calm herself down. Then, every time something doesn't go according to plan, Twilight takes a deep breath. Then in the climax, when it becomes clear that her friends mistook a random tourist for an important Inspector, Twilight takes a whole bunch of deep breaths to stave off a complete meltdown.