I use one specific strategy which works well in low volatility markets. Well, the entire market goes into high volty a couple of months ago.
So I'm smart. I don't use the strategy.
Now I'm stupid. I use another strategy designed for high volty markets. After all, it's very popular, and other traders have used it with success. BUT over the past years it has been a loser for me. It just hasn't worked for me.
"Now is my chance to expand my trading skills. I just know that it will work for me now. I can do it."
Anyway, you guessed it.
Two straight losing months, and now I'm back making up the losses.
Lesson: stick with what is profitable, stick with your trading plan. Stay out of the market when it does not suit your plan. If you want to "try something else", paper trade, or something.