One of the biggest steps for me to realize in the journey of improving my trading psychology was learning to take profits.
Knowing when to cut yourr losses and when to take profits with a position that is in the green is very hard.
You don't want to close your winning positions prematurely. But what you have to know about unrealised profits are: It is not real, until it is "realized".
And what's important about the losers, is that, you can't just sit on your hands and do nothing about the trades that are going south right in front of your eyes. You need to cut them as quickly as possible, learn what lesson you need to learn about them, digest, move on, don't let it devastate you. But act quick. If you do nothing and just wait, hope to god that It'll turn around, it might get actually depressing and crippling for your margin.