I tend to just mind my own business in the gym, and frankly in life also. Someone wants to dance on the treadmill, f#&% it shine on you crazy diamond at least you made it into the building. I tried shadow boxing with 15 pound dumbbells once, got the strangest looks. Who cares, who cares, who cares, not your life, not your problem. Most people, myself included it takes every ounce of will to get them in that building. And no one wants to be judged.