I have poor posture when I work. When I’m at my desk, I tend to hold the mouse with the weight of my arm resting on the desk at the base of my wrist. The problem is that after a while, my wrists get sore (I do the same with my left at the keyboard).
It’s been a problem for years, but it seems to get bad sooner in the day. What I need to do is just learn better posture. I need to hold my arms up when I’m at the computer. It’ll take some time to build up my muscles but I’m sure it will be worth it in the long run.