The idea that people often sabotage their own success gets some scientific backing in this study. Seems what you believe about your ability to improve your intelligence strongly affects how you react to both a) poor performance, and b) success.

People who are convinced they can improve reacted with improved performance after being told they had, in fact, improved their score on what they were told was an IQ test. People who think they are always going to have the same abilities got really nervous when they were told they had improved.

And now the kicker. When the first group, who believe they can get better, were told that their score on a second test had gone down, they got really nervous and actually performed worse on the next round!

This is good news for all those hundreds of life coaches appearing recently whose mission is to get people to change. All they have to do is convince their clients that all they need to do is change their underlying assumptions about their own abilities.