Thinking Too Much

When a person gets nervous about performing, he naturally becomes extra self-conscious. He starts to focus on himself, trying to make sure that he doesn't make any mistakes. He begins scrutinizing actions that are best performed on autopilot. This kind of deliberation can be lethal for a performer. The opera singer forgets how to sing. The pitcher concentrates too much on his motion and loses control of his fastball. The actor gets anxious about his lines and seizes up onstage. In each of these instances, the natural fluidity of performance is lost. The grace of talent disappears.

Jonah Lehrer
How We Decide