To anyone suffering RSI, get into physical therapy. They'll teach you valuable stretches and exercises that will be useful for the rest of your life.
Probably the single most important thing is this: try to deal with injury before it becomes chronic. If your wrists seem sore or you get tingling sensations, seek help before you develop an injury that's going to take months or years to heal!
The problem I have with this is that I don't feel much difference between regular fatigue and pre-chronic-injury kinds of damage. Typically by the time I can even identify the discomfort as non-transient, I'm already in for weeks/months/years of recovery.
I have managed to cause instant tendinitis where it basically felt like intense muscle pain, but that was a rare shock-load situation.
Most fatigue is just a drained feeling, followed by some muscle soreness for one to three days. Soreness in tendons and joints is almost always a problem, in my experience. If it doesn't clear up in about three days of relative rest, you're heading into chronic injury territory.
In my experience, if it doesn't clear up in three days, I'm already there (and usually also have no fucking idea what I did to cause the injury).
The more I look into this, the more I suspect that in my case it's a sensory deficit, i.e. I literally can't feel the initial pre-injury discomfort that trains most people not to move/position their bodies in ways that acutely damage joints or connective tissues.