Usually I am preparing myself to the process of trading, I listen to the calm and positive music, usually I am drinking green tea with mint. You can think that I am kidding but this is real, I'm trying to be as calm as it is possible.
Its look like easy to control our emotion but not so easy. I think it need a good experience in trading which can make you able to control yourself and take a right decision in a right time. So having good experience in trading can enable you to take a correct decision on time.
It is not possible to get rid of your emotions entirely and that it is better to practice the ways which can then help you in controlling your emotions as it is the only thing which can then save you from any such kind of decision which can result in loss of money. It is the most difficult thing to do but you have to master yourself so that you can get what all you expect to have.