I started boxing lessons at a gym near me when I was 345 pounds. Not once did the instructor or anyone else taking the class give me crap about being a fatty. I just focused on doing my own combinations and drills, and I drenched the floor, bag, and anyone unfortunate enough to get too close while huffing and puffing like a freight train. 5 months later and 50 pounds lighter, I still do that because I can go faster and harder than before. Not once did anyone give me crap, even the people in my splash zone. Trust me, the only people nicer in the gym than martial artists are the macho bros. So in other words, why do you care what other people are doing when you should be focused on what YOU'RE doing?