Fitness instructors use many tactics to elicit a response from their clients, but that doesn't give them the right to embarrass or bully someone in front of a class. If it happens, leave, and if you can, file a formal complaint about the instructor to their superiors.
Your classmates are total jerks
I'm not talking about the kind of people who are a little bit cliquey with their workout friends and simply don't go out of their way to include you. I'm talking about the types who harness their inner Mean Girls and make a point of harassing or ignoring you to the point of obvious shunning.
Lillian M., a self-proclaimed "faceless bureaucrat" for the US government, shares one such experience, "I got there before class started, so I sat on my mat, while the other people (who all knew each other) socialized amongst themselves and gave me major side-eye. I tried striking up a conversation, but no one was interested in talking to the new girl. It was capped off by the instructor looking at me like I had just walked out of a UFO and saying, 'Oh, you're new,' before turning around and not speaking to me again."