I started getting some wrist pain today. I knew it was from using the computer here at work, but I had no idea what in particular was causing it. Understand that I've been using computers extensively all my life. I taught myself to touch-type at age 12, and I've had stints of both longer and more intense computer use than I've been doing here at work, and I've never had any problems before.
But, as I picked up the mouse to do some after-lunch work, I finally figured out what's causing the problem.
The scroll wheel on the mouse.
Compressing my hand by scrolling with my third finger is causing my wrist all sorts of discomfort. It'll be a tricky habit to break, but I'll certainly work on it. The alternatives are not happy-making. (Thankfully, there is no willpower involved at home, where my mouse doesn't have a scroll wheel and the point is moot.)