In the mid 90s I had bad hand pain, so bad that most of the day I could only type with one finger. The FSF hired typists for me part of the day, and part of the day I tolerated the pain. After a few years I found out that this was due to the hard keys of my keyboard. I switched to a keyboard with lighter key pressure and the problem mostly went away.

My problem was not carpal tunnel syndrome: I avoid that by keeping my wrists pretty straight as I type. There are several kinds of hand pain that can be caused by repetitive stress; don’t assume you have the one you heard of. (source)