I've seen that episode with Seinfeld and it's interesting to see him being himself. Like most great comedians his onstage persona is immense, but it's an act. Anyone who chooses to pursue stand up comedy has to be so persistent, it's a hard world. I remember Martin would say as a comedian you couldn't have an off night, you had to kill every night. I can see why he was so anxious and nervous, it had to be nerve wracking!

Confidence for the most part is feigned, it's something I learned early in life. You may have absolutely no idea what you are doing, but if you act confidently people will trust that your do!