I am convinced that
my RSI was physical. I'm not convinced it's physical for everyone. Which is exactly what I said ("It's not").
There's no question, ZERO, that it's anything but physical in my case. It's worth mentioning (again, by the way) that I have debilitating problems with my right arm following an old injury. Some of us have real physical problems that cause real physical pain. I understand the mechanics of my unique situation well, and took careful, deliberate steps to physically address those limitations.
Finding the right equipment was not something that happened overnight. It was a long process that took at least a year. I could feel, physically, when new approaches were working and when they weren't. I could feel, physically, when introducing certain parts of the setup introduced new problems, etc. For example, while playing with my keyboard and mouse, I started fixing my wrists at the expense of my shoulders and neck, which then called for the leaning discipline, standing desk, and so on and so on.
Otherwise, good sleep and good food help me maintain the focus that's required to keep myself from slipping back into bad habits. One of the worst habits of mine, that's been the toughest to shake, has been stopping myself from leaning into the screen while getting into my work. It's terrible for my neck. Leaning back helps immensely. I can stay on top of this easily when I'm properly energized. I slip when I'm tired or it's getting late.