Only a fifth of women in the UK are doing enough exercise to be healthy, a report has found.
The Women's Sport and Fitness Foundation wants a public debate on how to engage women in physical activity.
It says many women currently feel under more pressure to be thin than healthy and are put off exercise from an early age - typically by school sport.
And women desperately need greater sporting role models than the wives and girlfriends of football stars, it says.
More than 80% of women are not doing enough exercise to benefit their health, and young women are only half as active as male counterparts.
Government guidelines recommend 30 minutes of moderate exercise five days a week, but only one in five women currently reaches that target, a survey of over 350,000 people found last year.
Separate research commissioned by the WSFF has found that 90% of women feel under pressure to be thin, and 25% say they "hate the way they look" when they exercise.
Some 40% of girls as young as seven, meanwhile, do not want to be seen as sporty.
"There is a fundamental mismatch between girls' views of their bodies' functions as passive and decorative, and the use of the body as active and functional in sport," the report says.
"Many girls also dislike the practical requirement of having to alter their dress and appearance in a way that conflicts with their images of femininity in order to take part in PE."
Cooke v Murray
One of the problems is a world dominated by male sporting heroes and their glamorous partners.
"WAGs are becoming the new sporting role models and that is depressing," said Sue Tibballs, chief executive of the WSFF.
"We need the media to pay greater attention to female sporting achievements. Why, when Nicole Cooke won the French cycling tour on the same day as Andy Murray hurt his wrist, did she become an afterthought on the news?"
The WSFF believes that cultural representations of women have to change if women are to show a greater interest in fitness than thinness.
It hopes to kickstart a debate involving the media, government, schools and universities, and also plans to encourage businesses to facilitate more sporting events at work.
It wants to make sport more accessible to women with children by encouraging the provision of crèches at leisure centres and more options to exercise as a family.
Prime Minister Gordon Brown, who is opening the WSFF conference on Thursday, has said his government is committed "to achieving a step change in how women and girls experience and participate in sport".
Minister for Sport Gerry Sutcliffe said: "One in five women participating regularly in sport is not enough.
"Getting more women doing sport is one of my priorities. We have to change the notion that sport is something for men and find ways in which it can be more appealing to women.
"This will need a joint effort from government, sports governing bodies and the private sector to make this happen."
Double Olympic gold medallist Dame Kelly Holmes said: "We need to find out ways to encourage girls to do exercise with their friends, to go to the gym, go out for walks, go on bike rides - things that you can find that are fun."