annoying old people

I got to exercise class late on Monday. It's a very tough class that involves a lot of jumping around & lunging & hoisting a medicine ball through different positions. It was also really crowded & I got several dirty looks for joining in. Then this old lady, maybe 60-ish, came in after me. She didn't do the exercises. She'd just kind of stand there, halfheartedly lifting a ball once or twice, lunging about 2 inches forward, that kind of thing. I wanted to scream at her. "If you're not going to do the exercises then stop taking up space! Don't just stand there getting in the way!" It was really clear after about 5 minutes that this was not the class for her, whatever the reason was. Plenty of other people left when they figured that out. She was so irritating, standing there like a fat deer caught in shouted commands.