My hands hurt just looking at that video...
At no time during any of these years have I ever encountered symptoms of RSI, or required any special breaks. I have terrible posture and I don't go to any lengths to protect myself against RSI, either. I've wondered if perhaps moving in a more digitally-inclined direction has somehow led to us being more conditioned to deal with these repetitive movements, or if I'm just lucky (or, more scary to think about, destined for some sort of horrible crippling onset of RSI at some point soon)?
This book has been useful to me:
http://www.amazon.com/Carpal-Syndrome-Therapy-Computer-Profe...
And in it they mention that some people do all the wrong things and never seem to get RSI. Better not to count on luck, though. I now wish I had taken preventive measures much earlier. I have my first physical therapy appointment next week...
Most people can walk a very long way without becoming too tired, even if they could only run or cycle a short distance. Their threshold for that kind of activity is low enough that walking just doesn't tax them.
Personally, I have a limit on how many push-ups or crunches I can do in a set: with training over the years, the numbers have gone up, but I always start to feel it after a while and eventually I have to stop. However, I know people who can outlast a bleep tape and still be doing crunches with correct form and only a little tiredness. It's so easy for them that there is negligible cumulative fatigue.
Personally, I've been using computers since I was small, and I also play a musical instrument and play sports that involve a lot of arm/wrist/hand movements. I've never adopted the kind of "bad habits" that many people of my generation who only started typing lots as adults have: I've just always kept my hands relaxed, wrists aligned, etc. because using my hands and fingers efficiently comes naturally to me. Maybe we're both just lucky, but I suspect we also have bodies that have adapted to this particular kind of task from an early age and we've never got into the kinds of bad habits that tend to exacerbate any natural predisposition to RSI. Which is still lucky in a way, I suppose.
I don't think it has to do with habit; a lot of RSI sufferers, myself included, started using computers very young. Humans have evolved to walk long distances, but we haven't evolved to sit all day holding our arms in front of us in a relatively static position, doing repetitive wrist and hand movements. If on top of that you don't exercise, have weak muscles overall and bad blood flow... Well, that's asking for trouble.
Or your like those people who never have problems with their teeth or eyes despite abusing both. Some people are just built better, other people have weaker systems like skin prone to excema, but since it is internal it's less obvious.
I said "hands" above but maybe it was only his keyboard (left) hand.
I think that with the right gear and proper technique, you can easily avoid RSI, just look at typists they do 300 apm easy :)