This is the most difficult part of the whole trading game for most of us. Your money is on the table and it is time to panic. Reminiscence of a Stock Operator has a great quote on comparing the professional to the amateur on this point. He says that for amateurs when the price moves against them they hope it will come back and when they profit they fear the market will take it away. They end up cutting their profits short and letting their losers run.
Professionals are just the opposite.
When they are losing, they fear the market will take more and when they are profiting, they hope it will continue. If you are successful at ignoring them, they will start to go away. What you must do as a professional trader is follow your rules regardless of what you feel like. Here is what I do. I review my trades at the end of the week and see if I followed my rules exactly.