If your league is causing you tension in your life, the best, faster, and easiest way to remove is QUIT LEAGUE PLAY. One night in my long life I tried the SHARKS LEAGUE in Phoenix.
It was disorganized, mismanaged, and a total Cluster Fook. Told the lady running I was not coming back, and the entire experience in a matter of 3-4 hour was a total joke. I am OCD about not being disorganized, and everything in is prober assigned place! Quit it, and it never stressed be again by league.
Learning the Mental part of Pool is a tough challenge, like any skill it can only be learn through Practicing until it becomes second nature. Easy for some, never accomplished by many.
If you enjoy League, then all you need do is working on what I will call being focused, not distracted.