Researchers have long advised middle-aged women that regular exercise decreases the risk of breast cancer. But now they’ve discovered that being active beginning at age 12 substantially affects breast cancer risk as well. In a survey of 65,000 women aged 24 to 42, those who had regularly exercised as teens and young adults decreases had a 23 percent lower chance of getting pre-menopausal breast cancer than those who'd been inactive.

This is sad news if, like me, your idea of exercise in high school was to walk to 7/11 and buy a loaf of Wonder Bread and a jar of marshmallow Fluff. (And that, folks, is the result of having strict health nuts for parents. Be forewarned.)

If you have daughters between the ages of 12 and 22—the years when regular activity has the greatest affect on pre-menopausal breast cancer risk—you don’t have to go hire them a personal trainer: just encourage them to do at least three hours and 15 minutes of vigorous activity a week, or 13 hours of walking (well, I did go to 7/11 quite a lot). While older women are encouraged to exercise to reduce fat tissue, a main producer of estrogen, the theory behind the benefits of youthful exercise is that physical activity itself lowers estrogen levels. Perhaps this has something to do with the fact that once I got seriously into yoga, my boyfriend became much less irritating.

Photo: www.more4kids.info