This is one of the best tools out there, and one of the easiest thing to learn but the hardest to implement. Well to be honest, I'd find it very challenging at first. I've struggled a lot in terms of trying to use the stoploss. But the fact I'm eager to regain my losses it turned out to be a disaster. After that I'd humbly surrender to it, I practiced stop loss for months fighting of frustrations and everything. But yeah bottom line is that no matter how good you are, we may still encounter even one mistake and all will crash. So yeah learn not to trade with emotions that will surely be not a good idea.
This is exactly why we use a stop loss, no trader is perfect and it does not matter how good you are eventually you will make a mistake, now you may be lucky and the market does not go strongly against your prediction and you lose only a small amount of money.
However what if your prediction was completely wrong and a huge movement begins to take place against your prediction? That single mistake can be more than enough to lose weeks, months or even years of efforts, and a stop loss is there to act as your safety net so this does not happen to you.