An army of motivational speakers and writers urge you to have confidence. With confidence, they say, you can move mountains, cure cancer and of course get rich without working. Like snake oil salesman, they persuade you that you can't do anything without confidence and the only way to get it is to buy their products. Millions know it's hokum but, in a bizarre version of Pascal's wager, they pay up just in case it works.
It's still bunk. The best work isn't done when you're confident. The best work comes from pushing yourself beyond what you know you can do. But don't take my word for it. Here's Steven Spielberg:
"You know how many movies, I woke up in the morning, gotten to the set and said, 'What the bloody hell am I going to do today? I have no idea how to attack this scene.' All the planning that I did from the safety of my office is no longer valid because the day, the weather we have, the new ideas the actors came to the set with that morning, have trumped every single of my best laid plans and I have to start from scratch."
"I get stage fright every single morning. If I didn't have that, I wouldn't be a director. You can't make a great movie from a position of great confidence. The more nervous I am, I think the better the films turn out. Confidence sometimes is a bit of an enemy."
Sports coaches will tell you the same thing: Confidence is an outcome. It's what you get after you've done the work, taken the risks, pushed yourself beyond the comfortable, the planned and the knowable. It's your reward for courage and, if you use it correctly, it will encourage you to take big leaps next time. But it will never offer guarantees, real or imagined.