This has already been passed around but it is worth a second or tenth read. Bill Murray continues his assault on everything stressful.
What's the point of spending your money on a class or on headshots if you get freaked out in the doing of the work? If you do, screw Meisner/Adler/Checkov - every smart thought they have is academic if you are tense. Prioritize your sanity over everything. The good work follows from there.