Or I'd do projects like paying attention to corresponding fingers and toes, but not with the sort of dedication where the projects would be likely to make any difference-- they were an effort to avoid boredom.
Actually, "just paying attention" is believed to be able to make a large and lasting difference. I can immediately adjust my posture, in various ways, by focusing on different points on my body. Without voluntary contraction of muscles, the muscles adjust. In fact, adjust much better than if I try to "do it" voluntarily.
Discussion of buckling-spring keyboards, which give accurate tactile feedback. You can get them for about $70, and a lot of people swear by them.
Here's my RSI story: Some years ago, I was getting a lot of pain in my right elbow, presumably as + result of excessive Blockout (3D tetris), counted crosstitch, and being polite for no good reason to someone I was very angry at when I was under stress. Rest was not helping. I remember needing to sign a bunch of checks, and using my right hand for the signatures and my left for the account numbers, and it was still hard on my elbow.
The Way of Energy is an excellent introduction to Taoist standing meditation. I worked up to being able to do twenty minutes of just plain standing and twenty minutes of holding a balloon (arms circled at a little below shoulder level) a day. After mere weeks, my elbow problem went away and never came back. Subjectively, I hit a point in meditation where it became obvious to me that I was using more effort to stand than I needed to, and I could just let go of the excess tension.