The Psychology Of.....

This is a subject that eventually everyone will be confronted with.
I see a lot of parallels between a trader and an athlete. You have to work hard to acquire a small edge, you have to stay in shape, mentally as a trader and physically as an athlete, and you have to be able to adapt to the circumstances.
A great trader can make money in any market, equally a great athlete can compete to win on any surface or under any weather condition. No athlete or trader always stays on top. Everyone has losing streaks and 'slumps' which certainly impact confidence, psyche and mental makeup. During those times it is so important to go back and remind yourself of what it is that gave you an edge in the first place. When you're slumping it's very easy to loose sight of that. In my own experience 9 out of 10 times when I have lost money in trading was because I did not follow my own rules and followed my emotions instead. That's when it's time for the penalty box....
Highly recommended: Dr. Steenbarger - The Psychology of Trading: Tools and Techniques of Minding the Market
Dr. Brett also runs an excellent blog, listed as 'traderfeed' in the Links section to your right.