I think the leading cause of frustration and getting overly emotional during a round of golf (and could be argued for life in general) is trying to control things that are entirely out of your control.
Something I've had my players do is to make two columns on a sheet of paper. One side is titled "Controllables" and the other side is titled "Uncontrollables". And then list everything that comes to mind that falls under each of those categories.
Once you have both lists, I think your first big realization will be how many of the uncontrollables you spend your time and effort attempting to control. And once you come to terms with what's actually in your control, your responsibilities suddenly get a lot fewer. You're actually able to relax and focus on what's important.
Write this actual list. It helps to see things on paper rather than floating around in your head.
Focus on what you can control and let go of what you can't control.