Someone in your early life probably drilled into you the importance of having proper posture. Ignore them at your own peril, especially when you’re young and haven’t yet gotten out of bed to say, “Ouch.”
For many programmers, coding becomes an obsession. For most C programmers, it’s quite easy to sit and write code for many hours straight. Such a stationary position is hard on the body. So, every few minutes, take a break. If you can’t manage that, schedule a break. Seriously: The next time you compile, stand up! Look outside! Walk around a bit!
While you’re working, try as hard as you can to keep your shoulders back and your wrists elevated. Don’t crook your neck when you look at the monitor. Don’t hunch over the keyboard. Look out a window to change your focus.