[swah]

I never had pain on my right hand which I use for mousing. My mild pain is the left hand - two hypotheses: this hand is weaker, and too much alt-tabbing.

I suspect lifting weights already improves this generally, as I have periods of much less pain which coincide with being more active.

[bitwize]

I had wonky, comes-and-goes knee pain which cleared up when I hit the gym and started doing squats.

If you have a body pain problem, "see if lifting doesn't help" is good advice, but you have to be careful, i.e., don't be a dumb gymbro and load on more weight than you know you can hamdle with good form.