One of the biggest issues I needed to overcome (and am still working on) is handling the adversity much better in my rounds. It's golf, and no matter what, bad breaks are going to happen in pretty much every round you play. How you RESPOND to it is what matters.
When I get frustrated, I have noticed it sets off a chain of negativity. I realized that my frustration focuses my mind on the bad, and you get what you focus on. As a result, the downward spiral would begin. The right way to respond is to do the best you can to forget about it and focus on the next shot.
When I was younger and a less experienced golfer, I would dwell on the poor shots. It made my rounds a grind and it was very hard to score. However, I decided it wasn't getting me anywhere, so I started working on my attitude and focusing on the next shot. I try to live by Ben Hogan's saying, "The most important shot is the next one" (ball marker :)). I have not mastered it yet, but I'm working on it.
This summer I started a round with double bogey, double bogey, double bogey and proceeded to play the next 15 holes 1-under par. I finished strong and put together a decent round. When I was younger, I would have either walked off the course on hole 4 or shot 20 over because of my temper. But now I am aware I need to stay focused with a positive attitude on what I will do. I will always need to work on my patience and staying calm, but at least I am starting to see results.
As in golf, as in life. Developing a positive way of responding to adversity will produce successful outcomes. If you can "let it go" and focus on the good, you are going to save shots and see improvements in your life.