Answer Wiki. The system would be cued off the pilot's helmet, so it will definitely look where your head is pointing, not your eyes specifically (that would be a gaze-tracking system, which AFAIK hasn't yet been used for this kind of application).
Exercise to Gain Leg Weight. Although you can't make your body gain weight in your legs, you can perform exercises that encourage the growth of leg muscle. Squats, lunges and step-ups are examples of such moves that target the legs and recruit a lot of muscle fibers for growth.
Leg (right): total mass 29lbs, of which 23.0 is lean tissue, 4.6 is fat and 1.4 is bone mineral content. Leg (left): total mass 29.1lbs, much the same as above except 1.5lb BMC. So if you're around 170 lbs and exercise regularly, you can probably expect your legs to weigh about 30lbs each.