By not sitting at the computer 18 hours straight. I eat well, I also fast 16 hours per day, by skipping breakfast, and eating a healthy lunch and dinner. I also take pushup/pullup/situp breaks throughout the day. Especially if important if you're going to be putting in long hours at the screen. Also get out and do some longer hikes 3-4 times a week. If it's the winter season, I'll row indoors on a rowing machine, or breakout "Insanity" :)