@Arne: Well, at least you can use your right hand as a plan B if your dominant starts to hurt and such. With the added benefit(?) of having to take your time with the lines. And, since you didn't mention any problems, I assume that the "messing up your polarity" thing is a myth

Since the discussion is already dying out, I'll sum up what's been said here, for posterity

:
Prevention:
-Pace out your work, don't overdo it even if your arm is just fine (because it won't be). You can use a break timer program for this. You might think this slows up your work, but it pays off in the long run (reflect upon this the next time your arm hurts).
-Do some stretching exercises, maybe between breaks, to help prevent any problem.
Healing (or prevention as well):
-If you're gaming, try alternating different devices so you don't keep straining the same areas.
-If you're drawing, you could try using your non-dominant hand. It will probably take a long time before you develop the fine motor skills needed (maybe more time than it takes your arm to heal), but this way you'll be able to keep working and rest your wrist at the same time (but don't start overworking your other arm as well!).