A woman I work with is put off running because she's worried about what people will think of her size. She's actually not particularly overweight, but she feels other runners will judge her negatively. I don't think people will. Surely the non-judgey are fine and the judgey will be glad to see larger people exercising?
I'm more impressed the bigger people are as what they're doing is much harder, but then again I'm 4 stone overweight myself.