A good read (PDF) from Brett Steenbarger. An excerpt:
It is not at all unusual to find that a trader is losing with a trend following approach because he or she is acting out unmet personality needs in the market. One of the best trading strategies one can employ is to find adequate outlets for attention/affection, achievement, self-esteem, emotional well being, and excitement outside of trading. Sometimes traders I talk with try to impress me by explaining that trading is their entire life. They do not realize that their very ‘passion’ and ‘obsession’ with the markets are likely to sabotage them, imposing undue pressures and interference. If you have a trading system and you faithfully execute that system, trading should be reasonably boring and routine. Better to enjoy roller coasters outside of market hours than ride them with your equity curve!