Hold the kettlebell in one hand at your waist, feet shoulder-width, knees soft. Pass it around your body in a circle, handing it off from one hand to the other behind your back and again in front, keeping the path close to your torso. Keep your core braced so your torso doesn't twist to help the handoff along -- your hands and shoulders should do all the traveling. Go a few circles one direction, then reverse. A tight path close to your body is what keeps this a shoulder and core drill rather than an arm-flinging one.