Yeah, carpal tunnels are not fun, but lets take this opportunity to talk about advices.
For my case, I work in a cell phone company so I am almost constantly in front of a computer screen. Every now and then its good to stand up and have your back straight (I don't think Runninghead mentionned about spine problems). May it be on computer, or on paper, we often tend to bend our back forward.
Also, every now and then its good for the eyes to look at the horizon, resting your muscles and simply gazing through the window at the scenery outside. Taking walks every day outside will force you to look away as far as possible, so its a good change for your eyes so they don't suffer from miopia later on. I am only 26, but I have noticed that already my eyesight is not what it once used to be so I need to take care of them.
When drawing on paper, I often put my hand with the fingers spread in order to ensure a certain distance between my eyes and the paper itself. Its good to have at least 25cm, or maybe more (maybe someone can tell more).