In high school, I used to get terrible anxiety when it was time to go to gym class (phys ed). There were two reasons for this: 1) I was two years younger than my classmates and 2) I was clumsy and especially inept at sports. I read about a breathing exercise to decrease anxiety and it worked very well for me.
Exercise #1: Breathe in for a count of four. Breathe out for a count of four. Breathe in for a count of four. Breathe out for a count of four. Go limp.
Later in life, I learned Breath of Fire. this is how I learned it:
Picture the full moon. It starts out full, then it gets smaller and smaller until it looks like a crescent. Then it is gone (the new moon). Then it begins to grow again until it returns to being full. Then the cycle repeats forever.
Breathe in for a count of four – waxing moon (growing).
Hold for a count of four – full moon.
Exhale for a count of four – waning moon (diminishing).
Hold empty for a count of four – new moon.
Repeat two more times. Breathe in for 4, hold for 4, exhale for 4, empty for 4.