After age 30, too-little exercise is a bigger factor than body weight when it comes to a woman's risk for heart disease, concludes a study in the British Journal of Sports Medicine. The Australian study team analyzed nearly 20 years of health and heart disease data on more than 32,000 women. The researchers found that, for women older than 30, physical inactivity was a bigger contributor to heart disease rates than high BMI or even smoking. Spending all your time being one with your couch is not worse for your heart than smoking, the study authors say. Rather, their findings indicate that, statistically, a lack of exercise is a bigger contributor to population heart disease rates than puffing on tobacco. Put simply, physical inactivity is more common than smoking, and so a lack of exercise leads to more cases of heart disease. The bottom line: For women over 30, exercising regularly is among the most important steps you can take to protect your heart. And the more you exercise, the more your risk for heart disease plummets. Try for a bare minimum of 30 minutes of moderate exercise a day, no fewer than 5 days a week. A full hour of exercise every day is an even better goal.