They truthfully just may not be use to seeing that type of attire. However, do what's best for you. If wearing Jean's allows you to be comfortable and workout then no one's opinion should even matter. Keep up the Good work!!
Growing up (like in middle/high school) we weren't allowed to wear jeans in the school gyms because it supposedly wore down the cushion material on the machines faster. Maybe that has something to do with it.
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