The Power Pose is something I tried and it worked! Heading into a potentially contentious meeting, I excused myself to use the bathroom and spent 2 minutes doing this. The meeting went entirely different than I anticipated -- in my favor.
I can do something for 2 minutes! This video is 21 minutes, but is well worth the time http://www.ted.com/talks/amy_cuddy_your_body_language_shapes_who_you_are.html
Whenever I am in a situation (or just having thoughts run through my head) that make me feel uncomfortable, I try to remember the Power Pose! It is amazing, it does make me feel much better!