A new report says lots of girls are dropping out of sports at school and are less likely to be active as they get older.
Whether it's getting too sweaty; not wanting to have a shower; or when things sometimes get too competitive - there are lots of reasons why girls say they don't want to take part.
But the organisation that did the research, Women In Sport, found that almost three-quarters (74%) of girls do want to be more active.
They say they're working on ways to keep girls interested in sport for longer.
We asked you what would make you do more sport.
This chat page is now closed but you can read a selection of your comments below.
I am a boy and I enjoy sport. I asked some girls and they said: "If the boys pass more we may enjoy sports more!"
Ismaeil, Birmingham, England
We don't like people being bossy and showing off, getting sweaty and not being able to freshen up, and not having more choice about which sport to do.
Year 5, St Catherine's, Swindon, England
I really like sport, but sometimes boys show off to much which puts me off. Never mind that, P.E. Teachers are strict which means lessons are boring.
Olivia, Eastbourne, England
I like school sport like netball and basketball, but I get put off by the activities that we have to do. It doesn't help that I'm very clumsy.
Meriel, Cambridgeshire, England
I would do more sport but I can't do the ones I want to, such as boxing and fencing because there are no clubs to go to, or it is too expensive. Also if I did turn up and it was just be boys, I feel I would get judged.
Ellie, Cornwall, England
I love sports and it's quite upsetting to know that people can't even have fun anymore with it. I am a sports leader and am constantly trying to encourage the younger generation; I believe sport should be encouraged in school and out.
Katie, Shirebrook, England
I like sport but my school doesn't have a variety of sports for girls, like the boys do. If we had more sport choices. I'd be able to find one I love.
Sophie, Chichester, England