But if you're doing most of your typing on a smartphone, you'll quickly have more pressing RSI issues...
I took a few typing classes in school as a kid, but of course didn't pay attention. Like a lot of people I learned qwerty by osmosis, not through proper training, and so I accumulated all sorts of terrible habits: reaching across, shifting with the same hand, etc. I got to be really fast but this was just amplifying the damage. Right about the time things were getting really painful I picked up vim. For me at least, it wasn't so much that vim (or Dvorak or whatever) really makes all the difference, it's just that it forces a clean break with your old muscle memory. And because the pain is the reason you're willing to put in the effort to re-learn, you're damn sure to learn it properly this time. That's all it took for me. No pain since, still on a standard rectangular qwerty keyboard.