Today I moved my mouse to the left side of my keyboard, went into my control panel, and set my mouse to be left-handed. This is because my (right) shoulder is still giving me some grief, and I thought maybe I could favor it more if I stopped mousing with it. I also raised my chair up extra-high, so that my arm hangs as loosely as possible, using as few shoulder muscles as possible.
Of course, I've used my mouse with my right hand ever since the mouse was invented. (Actually, I invented the mouse! No, I'm just kidding. It was Dan Quayle.) Mousing with my left hand raises all sorts of coordination issues. I helplessly watch the pointer on the screen sort of spiraling toward the place I'm trying to click.
Then once it gets there, sometimes I click the wrong button. I've switched it so that my left index finger does the "left-click", which feels more natural, but of course that is on the right side of the mouse. So sometimes my brain gets confused. Not all the time, or I'd switch it back...just sometimes.
I feel very clumsy. But I'm getting a little better, with practice. It's even kinda fun! I'm not sure how much it's actually helping my shoulder though: I'm so used to reaching over for the mouse with my right hand, I find I do it pretty frequently anyway. It's just habit.