When a monkey hurts its foot on a tree stump, he flies into a rage and kicks the piece of wood. You laugh at a monkey, but do you laugh at yourself when you act like him? If the market drops while you are long, you may double up on your losing trade or else go short, trying to get even. You act emotionally instead of using your intellect. What is the difference between a trader trying to get back at the market and a monkey kicking a tree stump? Acting out of anger, fear, or elation destroys your chance of success. You have to analyze your behavior in the market instead of acting out your feelings.
We get angry at the market, we become afraid of it, we develop silly superstitutions. All the while, the market keeps cycling through its rallies and declines like an ocean going through its storms and calm periods.
– Alexander Elder, Trading for a Living