In addition to using text editors like vim or emacs and using a tiling window manager, what other programs do you use to reduce usage of the mouse? I recently discovered warpd which is similar to vimium's hint mode but works globally.
If that is the only thing saving you from RSI you're going to get it anyway.
I've had the pleasure, and your body posture and mental state of mind are much more important. Getting up every now and then is also important, changing seat position helps, and doing some sport also helps.
Both of my arms did hurt so much I could not cut my own meat. Mouse or no mouse:(.
I'm half-kidding about this though. I get that the stuff you mentioned are a lot more important. These are the reasons I started exercising and using break timers.
But the thing with learning keyboard driven workflow is that you tend to develop a habit of spam pressing keys if you can't immediately think of a way to something with less keyword. Especially in vim. Because if I'm not always pressing something, I don't feel like an expert enough, damn it! So I resorted to spamming hjkl, lol.
When my RSI problems start to develop. I had to really focus and change that habit to slow down and think of a way to press less keys. But still I stopped using vim key equivalents on browsers though, mouse scrolling relaxes my fingers a bit more than key pressing.
I use tridactyl in firefox.
Except for emacs and tiling wms I'm not too deep in applications for reducing mouse usage, I tend to use keyboards with 'better mouse placement' for example the tex shura which copies the thinkpad trackpoint, or a corne keyboard with a pimoroni trackball. Or a charybdis nano.
Even using a smaller keyboard layout counts imo, my favourite non-ergo keyboard layout is 60% which reduces necessary arm-travel-distance a lot :)