Interesting, I find I can type all day and not feel a thing in my wrists or hands, but just 15-30 minutes of continuous mouse usage, and I'm reaching for the pain medication. To me, staying able to use a computer without the mouse is about both speed and comfort.

This is a common problem in people who play computer games, especially those that are mouse heavy. The solution is pretty simple actually.

Simply lower your mouse sensitivity. Now you use your mouse by moving your entire arm instead of your wrist.

Watch how this guy uses his mouse: https://www.youtube.com/watch?v=X89152oocsA

Of course they do it to aim better, but it also puts less strain on your wrist and hand

In other words, you got old and slow. Happens to us all :)

This is one of the reasons I started learning vim bindings.

I can hunt and peck and still be relatively efficient at editing. So I can move my hands from the keyboard.