Lifelong B Player here...
For those of us that have scraped and clawed along the way to modest improvement, one thing that I think is so often overlooked is the FACT that there are shots that require constant attention! I think too many people think that you just master a particular shot and you then own it. Personally, I have to constantly work on long straight in shots, rail shots, jacked up shots, my break shot, and max english shots just to name a few. If I take a few weeks off -- I basically have to start back over -- tuning up all these shots. It's not like I can just continually work on mastering NEW shots. There's just not enough time in the day.
Secondly, I think we oversimplify the passion/apathy dichotomy. As I find it hard to believe that there is a pool player on the planet that could be passionate about the game WHILE constantly firing balls into the rails. Short of being autistic or having some sort of diagnosable OCD like disorder I think the original passion that many new players feel can ONLY remain long-term if the player is capable of improving. So it's my view -- that the psychology of a player is fueled at least as much by their ability as the other way around.
Every type of shot demands your full concentration and attention, every single time, in practice or play. Even pros miss shots when they take them for granted. Even straight in shots are unique in terms of the CB position that must result in order to continue the pattern play, always a consideration unless it is the game ball shot.
Since you say you are a life long B player, it sounds like you have been stuck at that level for a while. Do you really, really, really want to improve? Desire comes first. How long have you been playing?
Sounds like you have enough drive to drill on shots and have your own table.. The pros and some higher level players also do the same types of drills. They have shot enough to where they don't lose it all if they take two weeks off, but there is more to it that just grabbing the cue. If you have the desire, do you have the drive to do the rest of what it takes to improve? Much of that is mental.
I agree about the link between passion and performance. Note that I used the word 'performance' instead of your choice of 'ability' and this is because thinking of it in terms of ability is a slippery slope. It is a subtle but profound distinction, because the conscious and subconscious mind will believe what you tell it, and if you tell yourself that you have reached the limits of your ability, guess what happens?
The reality is that anyone is capable of improving, unless there is some sort of physical problem that constrains them. Even then, it is amazing what can be done.
The first time I met my friend Alan was in the city league as an opponent and he kicked my ass on the table. In spite of the fact that his head and stroking arm were shaking like a leaf while he was down on the shot. This was the result of a motorcycle crash when he was in high school, years before. Then he went in for a second round of brain surgery, which reduced but did not get rid of the shaking. He returned to pool league and continued to shoot well.
I was struggling with my shooting due to undiagnosed double vision that I overcame later on and got to the point where I was beating him at least half the time. I took inspiration from him because he demonstrated that my limitations were not entirely physical so I started working on my mental game.
His performance was all the more remarkable because as I found out later, not only did he have two rounds of brain surgery, both times he had to learn to talk, walk, feed himself and shoot pool all over again. He shoots left handed but is good enough at also shooting and winning right handed that the casual observer wouldn't know the difference.
Each shot is a process, staring with quieting your mind, working backwards from the game ball, picking the next shot, determining where the CB needs to land, planning 3 shots ahead, using a consistent and comfortable pre shot routine, addressing the shot, getting down on it, sighting, warm up strokes, figuring out how hard to hit it, what english, if any, is needed, standing up and starting over if something doesn't feel right, execution, follow through, staying down until the ball goes in the pocket. Rinse. Repeat.
If you get that process packaged in a way that works for you it is just a matter of executing it faithfully each and every time, and if you do, you will find that you don't have to start over if you take two weeks off.