The thing that can help control emotions is to have a lot of understanding of how good and correct trading strategies, have targets and limits in trading so that our logic will warn our emotions to stay on the right path and not be easily influenced to make a decision that is not relevant to the analysis and strategies that has been made.
What's funny is that most traders these days don't have a strategy or the ability to do analysis. I'm talking about newbies here, those who get into the market with the mindset that they can make a lot of money from it in a short period if they have enough money, they don't realize it doesn't work that way, and having money alone isn't enough to make them reach the other side and achieve their goals in a financial market as volatile as this.
Misguided newbie traders are often driven by emotions and their decisions are mostly influenced by gut feelings and not analysis or research. They lack the basic understanding of the trading principles which include learning which is the very first step and it can't be skipped because if you skip the learning part, all other parts will fall apart at some point.