you exit trading when you are extremely profitable. do not believe you are invincible, you are just lucky.
What do you mean by extremely profitable?
You should set some target limits for your profit but that target should be reasonable to achieve not like 100% or few 100% growth. If you're more greedy then you may not make a profit from your trades.
you also exit trading when you have lost more than you can afford. do not chase losses, the market owes you nothing and will give you nothing.
This way of trading is very dangerous. You should put some limit on your losses not that you need to wait until you lose a lot of money from a single trade. I usually set around 10% loss for my every trade to exit.