It is difficult as hell. Part of it because most traders are stubborn even if they are wrong (me included). If you can get out, when the loses are smaller----you will do better. That is my personal experience.
The ones that really hurt was when I did not bail out sooner on losing trades!!!
Everyone will have losing trades even the best traders but, majority of traders do not know when to fold them like in a poker game.
Also, greed is killer too!!! Set price targets so, you do not guess when you should get out!!!