Don't smoke or use tobacco products

"If you smoke, quit," advises Sharonne Hayes, M.D., a cardiologist and director of the Women's Heart Clinic at Mayo Clinic, Rochester , Minn. "That's the most powerful, preventable risk factor for heart disease."

No amount of smoking is safe. Smokeless tobacco and low-tar and low-nicotine cigarettes are also risky, as is exposure to secondhand smoke.

Tobacco smoke contains more than 4,800 chemicals. Many of these can damage your heart and blood vessels, making them more vulnerable to narrowing of the arteries (atherosclerosis). Atherosclerosis can ultimately lead to a heart attack.

In addition, the nicotine in cigarette smoke makes your heart work harder by constricting blood vessels and increasing your heart rate and blood pressure. Carbon monoxide in cigarette smoke replaces some of the oxygen in your blood. This increases your blood pressure by forcing your heart to work harder to supply enough oxygen.

Women who smoke and take birth control pills are at even greater risk of having a heart attack or stroke than are those who don't do either. Worse, this risk increases with age, especially over 35.

The good news, though, is that when you quit smoking, your risk of heart disease drops dramatically within just one year. And no matter how long or how much you smoked, you'll start reaping rewards as soon as you quit.