How to prevent fatigue while working 14 hours at a computer every day?

Computer fatigue: Take frequent breaks to stand, stretch, put neck/shoulders/back thru range of motion exercises to increase circulation. Eat nutritious meals (not junk or high carbs; they'll may you drowsy); protein, good fats from nuts. Energy drink or a bit of caffeine may give extra boost. Get good night's rest. If fatigue doesn't resolve, see fp to check for anemia, infxn, etc.