SCIENTIFIC AMERICAN has an article on exploding the self-esteem myth. Bottom line: "Boosting people's sense of self-worth has become a national preoccupation. Yet surprisingly, research shows that such efforts are of little value in fostering academic progress or preventing undesirable behavior."
Well, sure. Most everyone who has ever achieved anything great (or even merely good) has been a wee bit terrified along the way. Prior to every one of my (modest) accomplishments, there have always been moments in which I've been convinced that I'm worthless, an idiot, and absolutely going to lose.
Or, as it was memorably put in Field of Dreams (IIRC):
"Annie Kinsella: 'How many ballplayers feel like they're going to lose their father's love every time they go up to bat?'
Ray Kinsella: 'All of them.'"
Fear, low self esteem, self doubt: These are your friends. The trick is using them to your advantage.
(And, on that entirely inappropriate note, Merry Christmas.)