Plamen Petkov

Here's the ultimate motivation to work out: It can significantly lower your odds of getting breast cancer.

Women who did about 10 hours a week of moderate exercise had a 30 percent lower risk of breast cancer than their inactive peers, finds a new study.

Even if you work out less than that--walking and gardening count, by the way--you could cut your chances of developing the disease.

"Exercise can enhance immune response and DNA repair," says lead author Lauren McCullough, a doctoral candidate in epidemiology at the University of North Carolina Chapel Hill.

No worries if your sneaks haven't seen daylight for a while. Says McCullough, "Women can start now and still lower their likelihood of developing breast cancer, no matter their age."