Here's another one that never fails me:

Humor

I know it's near impossible to notice funny things when your chest is tightening up and your heart is racing, so it's best to start looking for something funny prior to that phase.

But at any rate, I notice an immediate calming effect when I distract myself with something humorous.

I've always believed that the best comedians have used humor as a kind of defense mechanism against anxiety and depression.

Maybe that's why good looking or very confident seeming people don't make very good comedians?