People who are under a lot of stress often tend to hold their breath or forget to breath. Then all of a sudden your body is like "hey I need some air" and you find yourself taking a deep breath. Do you sigh a lot? That can also be a sign that you are holding your breath a lot from stress.

Mindfulness and meditation strategies get you to focus on your breath. In-out. In-out. Even focusing for 5-10 minutes can make you feel a million times better.