When watching the pros on the PGA Tour, you will observe many players have the incredible quality of minimal emotion. They have great self-control. If you are an emotional player, there is a good chance your emotion holds you back from better golf.
Emotion comes from wild thoughts — Thats where it all starts. But controlling your emotion even when you have wild thoughts is very important. Even the best cant control all their thoughts, so controlling the emotion is the next thing to do.
If you hit a terrible shot or putt, don't throw the club, slam the club in your bag, stomp your feet, etc. Just say, "ahh" then take three deep breaths, then forget about the shot and move on. Remind yourself that emotion is weakness and just move on.
You will move forward, become more focused on the next shot, and won't dwell on your priors shots. It will feel like a release/weight lifted from your shoulders when you start to consistently do this. Your temper will disappear, and you will get more enjoyment from your rounds.