Preventing and managing RSI and/or other injuries

Hi fellow programmers.

How do you ensure to prevent RSI and/or manage RSI? Especially with your hands and arms.

For those who don't know, RSI is a disorder that occurs when repeating the same movements too much for a long period of time. This frequently occurs when sitting behind a desk and using keyboard and mouse the entire day.

I personally have a great (but expensive) chair with arm rests and have a slightly ergonomic mouse (it has a curve, to make it more comfortable for my thumb).

Honestly, I dislike having to disrupt my computer activities every hour, because I'm usually quite immersed / invested into whatever I'm doing. Whether that's watching a movie, developing an app or simply playing videogames. However, I'll probably have to start taking frequent breaks, in order to prevent RSI from taking a hold in my body. Unfortunately, we only get one body, one chance, so let's not mess it up with neglecting breaks and acquiring RSI.