A lot of “injuries” we have can be fixed with exercise.

This is why a lot of what PT’s do is teach you simple exercises to work ALL of your muscles, including those that might not get activated in our day to day existence, leading to problems.

It's like the body reaches a false equilibrium in which the injury doesn't heal completely unless you "knock it out" of the equilibrium again.

From personal experience: if you have mild pain from past injury/strain, don't give up on trying to fix it. Move a lot, improve your muscle strength and try to stimulate circulation. Be careful not to repeat the injury, but don't avoid the pain altogether (eg. by reducing the amount of movement). It's possible that the pain will improve or disappear, even if your injury didn't heal by itself for years.

(Oh, and go see a physiotherapist a couple of times if you haven't already.)

Me too posts are frowned upon on HN, but vote counts are hidden so I'll say for others: me too. I developed RSI as a teen from spending too much time at a desk with bad posture and have dealt with flare-ups into my adulthood. They were miserable and some days I had to take off work. Once I started bouldering, it went away within months. It's probably the forced blood flow in the area, but whatever it was helped tremendously. I can still hurt my wrist if I type in a terrible position, but it only hurts a bit and doesn't turn into the sustained RSI I had.

Building strength seems to help with all sorts of pain issues. I once banged up my arm pretty good in a fall; what helped was going to the gym and doing curls and extensions with whatever the arm could support: five pounds, ten pounds, whatever.