Following on from my last post, on the subject of recommendations, I can heartily recommend that Evoluent mouse. I developed tennis elbow last year (and not from playing tennis), which has largely disappeared since I moved to using an ergonomic mouse. Ironically, the tennis elbow was probably triggered by me moving from a vanilla flat keyboard to a Microsoft Natural Ergonomic keyboard. Decades of habitual arm positioning were abruptly overturned when I started typing more naturally, and my muscles resisted. Ironically I made the decision to change keyboard when I noticed my wrists were starting to ache a lot.
It's a good keyboard though, and I've bought one for work and one for home use. There was another downside, or maybe it's an upside. Because the keyboard splits the keys into two groups, I had my nose rubbed in just how bad my two fingered typing technique was, so after thirty-five years of keyboard use I've finally had to teach myself touch-typing.