Slow, quiet breathing helps relax the body and mind and ease pain. Lie or sit with one hand on your belly and take a deep, slow breath. Imagine filling a balloon in your belly with air. Then breathe out, as if you're letting all the air out of the balloon. Think of breathing out stressful thoughts and breathing in relaxation. Aim for about six long, deep breaths a minute.
If you have lung problems, talk to your doctor about what breathing exercises would be good to try, or if other ways to relax would be better.