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.
You'll probably gain weight in puberty -- most girls do. You may notice more body fat along the upper arms, thighs, and upper back. Your hips will grow rounder and wider; your waist will become narrower. Your doctor will check your height and weight each year to make sure you are growing properly.