I originally read this post in order to clarify what I should focus my sight on in game but since it developed this way I will just share my experience which seems somewhat similar. This all is based on my own experience gained during my life and by playing the game so there is not need four you to obey it. I hope I'm not being too obvious.
First of all, I want to emphasize something that is usually considered obvious but many forget about it. Play relaxed both mentaly and physically. Straining and stressing over failure, miss, not climbing rank or whatever will only make you angry and/or flustered which becomes another distraction. I also noticed when I play not caring so much I tend to get better results. Attitude simply affects anything you do. It's good to take a break when you are furious or feel it's just not right. Time solves most if not all the problems.
Secondly, If you want to calm your mind you might want to focus on what is now instead of what could be or your ambitions. By building your awareness you will be able to control your body more effectively and will not get distracted by pointless thoughts. You can even consider meditation which doesn't always have to mean what people tend to think it does.
Lastly, seeking improvement I found out it's best to appropriately train oneself without expectation of immediate results (they will come soon enough). Recently I came to like sorting beatmaps by difficulty and simply playing every map let's say 4.50* and more at least once until I'm satisfied. When playing I analyse my weak points and then train whatever skill I lack in.