Harvey Dorfman, the sports psychologist and author of such books as "The Mental Game of Baseball", gets calls from major league pitchers even when they are doing well.

"Here's the nature of a call when a guy's doing great," Dorfman says in an article in the Philadelphia Daily News. "They're starting to have thoughts: 'How long can this last?' Isn't that incredible? They can't even enjoy doing well."

Dorfman has helped coach people to think for the better and not the worse for many years and his clients include pitchers on the Philadelphia Phillies such as Raul Ibanez, Chan Ho Park and Jamie Moyer.

Dorfman works individually with his clients to help them understand the three elements of performance: approach, result, response. He teaches that you have control over your mental attitude and focus, that is part of your approach. You have no control over the result, however. The key is how you respond to the result, that you do control.

"Approach and response is entirely in your control," Dorfman says, "The result is not."

Sports psychology is a narrow application of the work psychologists do in general. The Bureau of Labor Statistics predicts there will be almost 200,000 psychologists employed in the U.S. by 2016.