It is very important to be aware of this. The market doesn't always continue in the bull market. It will start doing the opposite eventually. So I think that the best thing to do is setting some price goals. It makes things easier for an investor.
The problem with those kind of goals is that if they are too high then you are still going to have the same problem as before and if the goal is too low then you are going to sell to soon and you are going to regret it, you need to have a strategy that can adjust your goal automatically so you can catch most of the bull market but at the same time you can get out of the market before the bear market comes, if this sounds difficult believe me it is and it is why so few people can earn money in the markets.
It's true that it's not easy to determine a strategy that fits the goals we want to achieve,
especially if we just follow the strategies of other people it probably won't work,
better keep learning by trying to understand the market