It's hard to fall for your emotion especially when you are in the times of losing streak. But I'm dealing with it by simply stopping and changing my plans, it's the hardest enemy as we know we are fighting with ourselves. And I used to have a glass of water on my side, always. It makes me calm when I drink when something is making up on my mind with blowing with the pressure.
I agree, it is quite hard and if you follow it you will not be able to make a good decision. The sudden fall of the prices of the asset you are looking at will make you heart to drop as well. I guess you have to keep it call and just follow a simple strategy you will formulate. You should trade emotionless, it's just a job.