- use less the mouse, train for it if necessary. I find myself not even needing a mouse (I'm using a laptop, using trackpad when necessary, but I guess it's not your case)
- switch right/left hand with it, to release stress on hands, no need to be ambidextrous at all at the beginning
- have a different posture so that the efforts are not only on the hand/wrist, could be a posture with a more active back