A single push-up is a mini-gym. It loads the muscles of the shoulders, triceps and chest with up to seventy-five per cent of your body's weight. While a single push-up works, primarily, the upper body, it also activates the core and abs, works the glutes and quads and even places a little of the load on the feet and calves. Learning to do push-ups is essentially an exercise in strength training where you teach your muscles to resist the pull of gravity on your body's mass. This helps make you feel light on your feet, strong when you move and in total charge of your body. And it all begins in small ways of daily activity, carried over a month.