Thank you for sharing.
The mental side of pool is every bit as important as the stroke, yet because it isn't visible and you can't see how other players think it's importance is perpetually underestimated. Most of my improvement as a player has been through improved outlooks. Some of this is direct by having a more positive attitude and managing ego and expectations which allows me to deliver more of my game at the table. Some of this is indirect as keeping the right outlook towards mistakes and imperfections can inspire me to develop my game on the table.
We all have positive thoughts and negative thoughts. We perform better when thinking positively, yet there are many situations where negative thoughts and emotions come into our game. We have to acknowledge that and work on it as seriously as we work on our cue ball.
Any time you are experiencing negative emotions (such as frustration, anxiety, self loathing, etc.), that is a sign you are looking at something wrong. You won't have much fun, and you won't perform that well. My approach is to understand where those negative feelings are coming from, then scripting out and practicing a different thought pattern that will be more effective.
For example, in this video he used a situation in which he was poor at combinations. One train of thought is a negative pattern leading to "I am no good at these" which could lead to a path of under-performance, negativity, lower self image, and loss in motivation. Instead he has practiced another thought pattern of a learning outlook. He senses the negativity, finds the thoughts associated (you are no good at these), then deliberately replaces those thoughts with more positive and constructive thoughts (you have an opportunity to grow in this area, you aren't going to get worse if you practice these so what are you afraid of, etc.).
I myself have literally spent thousands of hours thinking, talking, and journaling about situations like these. Preparation for competition involves me visualizing situations in which negative thoughts would trigger. I have written out in detail exactly what thoughts I'll find myself thinking, how I'll feel. Then I'll journal about where those thoughts come from, why they are so distressing to me. Next I'll script out some more effective thoughts I'd like to think in those situations instead. At times I've even put these on flash cards, negative trigger on the front, re-framed thoughts on the back. When practicing at home I'll picture myself at the tournament, draw a flash card, and imagine myself feeling that specific fear or doubt, and thinking those negative thoughts. Then I'll practice the response in which I counter those thoughts with my true beliefs, then by letting go of everything and turning back to the shot at hand with feelings of calm joy and focus in the present. What's amazing is that after years of practice, those positive thoughts actually become who I am. I'm not faking it, the negative beliefs become weak, shadowy memories, and I actually identify with the positive person I've sculpted.
NOTE: The point of this is not to be thinking at the table or during the shot. This is not a superficial pep talk. The point is to use a positive thought to counter the negative thought so you can let it go, then refocus on the here and now and allow yourself to play the game as well as you can in the moment, unencumbered by negative energy.
And, as the original poster said, this is more than just pool. Pool is a game that allows us to develop competence and learn the language of success. These skills and attitudes apply towards life as well. Pool has been spiritual to me in some ways, but when praying in church or meditating in a yoga center you don't really know how pure your mind is. With pool you get direct feedback from results on the table as to whether or not your mindset is correct. How amazing is that? It's almost like God answers back, metaphorically speaking of course.
In the end I think more pool players should take the mental game much, much, much more seriously, then put in a lot of work as opposed to just arming themselves with a few cliches and going back to work on hitting shots. I think they could find more success long term, and more importantly more joy in each moment spent with this amazing game.
Great video and post OP.