An old proverb that may be, but applies too as a simple system to avoid repetitive strain injuries.
Sit, stand, change positions.
Rotate to a different input device (mouse, tablet, trackball) each week.
Take your eyes off the monitor and stare out the window for 90 seconds every hour.
Walk to lunch once a week, or go to a bathroom on a different floor of the building.
Over reliance on any one part of your body will ALWAYS cause damage to soft tissues given enough time.