"Under pressure, you don't rise to the occasion, you sink to the level of your training. That's why we train so hard."
The best way to stay calm under pressure is to avoid the situations that cause pressure
The idea of the Kata is to do it over and over again. The reason we do this... the red, green, refactor... is so that when my boss comes to me and says "Jim, I need this fixed in a day... can you get this done by this afternoon?" And I don't panic and just start writing random code, because I've got the discipline of practicing the TDD over, and over, and over again, it's actually much faster for me to fall into the good habits that I've developed by practicing the katas then to fall out of them and ignore all the good things that I know about how to develop software. That's the real purpose of the kata.
"An amateur practices until he can do a thing right, a professional until he can't do it wrong."