There's this idea in trading that you have to be an emotional rock -- Shut out your emotions and just think.   I've found that to be almost as frustrating and destructive as the losing trades.

Of course panicking doesn't help either, so since you asked:

I actually hired a trading psychologist years ago to help me through this  Seriously.  Through him I was able to understand the genesis of my emotional responses which helped me deal with them better.  Needless to say, this has helped me out in life tremendously. 

We can't will our emotions away, but we can understand why we feel them.  That + a good trading plan + understanding of markets tends to lead to a cooler head even in the face of losing trades and periods of drawdown.