What would make you do more sport?
3 March 2015 Last updated at 06:52 GMT
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, the Women's Sport and Fitness Foundation, 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.