“The choices you make in the first half of your life can really impact your health and freedom from chronic diseases in the second half of your life,” says Erin Michos, MD, a preventive cardiologist at Johns Hopkins Medicine in Baltimore. Prevention is key. The earlier you start taking steps to reduce your heart disease risk the better shape your cardiovascular system is likely to be in for the long haul. Consider this: 80 percent of heart disease is preventable, according to the American Heart Association. What can you do to beat the nation’s number-one killer? Follow this decade-by-decade guide to keep your heart healthy.

Your 20s and 30s: Lay the Foundation for Good Health

What’s Happening Now During your prime childbearing years, you’re less likely to have artery-clogging cholesterol buildup, thanks to plentiful amounts of estrogen. This powerful hormone helps keep arteries flexible and blood cholesterol levels low, according to the American Heart Association. Still, if during pregnancy you develop high blood pressure, preeclampsia (pregnancy-induced high blood pressure), or gestational diabetes (pregnancy-related diabetes), or if you give birth preterm (before 37 weeks), then “you’re at increased risk for cardiovascular disease later in life,” Dr. Michos says. Research published in Circulation: Cardiovascular Quality and Outcomes found that women with preeclampsia had a four-fold increased risk of heart failure and two-fold increased risk of heart disease, stroke, and death due to cardiovascular disease later in life. “Even if your blood pressure normalizes after pregnancy, you still have a two- to four-fold increased risk of cardiovascular disease later,” Michos says. With gestational diabetes, you have a seven-fold increased risk of later developing type 2 diabetes, which can increase the risk of heart attack. What to Do Now See a primary care physician. If you developed high blood pressure, preeclampsia, or gestational diabetes, or gave birth preterm, see a primary care physician after your baby is born (not just an ob-gyn). You may even want to see a cardiologist. Your mission: Track risk factors, including blood pressure, blood sugar, and cholesterol levels closely, Michos says. Eat to beat heart disease. Get into the habit of eating a Mediterranean-style diet, which is loaded with fruits, vegetables, whole grains, lean protein such as fish, and healthy unsaturated fats such as olive oil. Since you’ve got time on your side, developing heart-healthy lifelong eating habits in your twenties and thirties can help keep your arteries clear. Fit in fitness. Don’t smoke and carve out time to exercise aerobically at least 150 minutes each week and strength train twice a week. Taking these steps early on can be lifesaving later. “It’s a busy time in life, especially if you’re raising a family and working full time, but the things you do now can really impact how healthy you’re going to be in your sixties and seventies,” Michos says. RELATED: Heart Disease: The Diabetes Connection

Your 40s: Keep Track of Your Health Metrics

What’s Happening Now Unless you enter menopause in your forties, your risk of heart disease generally remains low throughout this decade. Still, if you’ve got a family, maybe even parents to look after, and a busy work schedule, it’s easy to let your health slide. What to Do Now Keep close tabs on your numbers. Get yearly checkups so you can track important numbers, such as blood pressure, fasting blood glucose, body mass index (BMI), and cholesterol. If your LDL “bad” cholesterol, blood pressure, or other risk factors aren’t where they should be, take steps to improve them. For example, change your diet, exercise more, or take medication to lower your blood pressure or cholesterol if your doctor recommends it. Here’s an overview of the numbers you need to know and your goals. Total cholesterol: less than 200 milligrams per decilitre (mg/dL) LDL cholesterol: less than 100 mg/dL HDL “good” cholesterol: 50 mg/dL or higher Triglycerides: 150 mg/dL Blood pressure: less than 120/80 Fasting blood sugar: less than 100 BMI: less than 25 If your numbers aren’t quite where they should be, “push hard on lifestyle,” Michos says, by eating a heart-healthy diet and exercising regularly. If lifestyle isn’t enough, talk with your doctor about preventive medication.

Your 50s: Kick Your Health Plan Into High Gear

What’s Happening Now After menopause, the risk of heart disease rises. With the loss of estrogen, blood pressure tends to go up, as do LDL cholesterol and triglyceride levels, while HDL cholesterol tends to decline, setting the stage for artery-clogging atherosclerosis. What to Do Now Avoid hormone therapy. Even though the estrogen that’s naturally made in the ovaries protects against heart disease, estrogen in pill form can increase the risk of heart attack or stroke. “Evidence suggests that hormone therapy after menopause doesn’t reduce the risk of cardiovascular disease or chronic diseases,” Michos says. Assess your heart disease risk. Even if you feel fine, you can still have heart disease that’s not yet causing symptoms. Plugging in your age, cholesterol, blood pressure, and other details into the American College of Cardiology and American Heart Association’s online risk calculator will estimate your 10-year risk of heart disease. At certain benchmarks, specific recommendations kick in. Your risk is low if it’s 5 percent or less and you continue to follow a healthy lifestyle. If it’s 7.5 percent, talk to your doctor about whether preventive treatment, such as aspirin or statin medication, is necessary. “A statin helps shrink arterial plaque,” Michos says. And if your risk is over 20 percent, your doctor will likely recommend aggressive preventive treatment, including medication and lifestyle measures. Ask about a low-dose noncontrast CT scan of your heart. This test measures calcified plaque deposits in your arteries. A high calcium score indicates that you’re at a high risk for heart disease.

Your 60s and Older: Keep Up the Good Work

What’s Happening Now The risk of heart attack is higher now. By age 60 to 79, about 71 percent of women have heart disease, according to the American Heart Association. The good news is that you still have the power to reduce your risk of heart attack and stroke. What to Do Now Keep exercising your options. Your heart needs the benefits of physical activity and a heart-healthy diet now more than ever. “Strength training is more important than ever now,” says Jennifer Mieres, MD, a cardiologist in New York City and co-author of Heart Smart for Women. It helps control heart disease risk factors and keeps your bones strong. In menopause, bones lose estrogen. “If you haven’t started strength training yet, add it now,” Dr. Mieres says. It’s not too late. Keep close tabs on your risk factors. The numbers you started tracking in your forties — cholesterol, blood pressure, fasting blood glucose, weight, and BMI — can mean even more now since the probability of heart attack is greater. Do what you can to stay in the ideal ranges. Keep working with your doctor to develop a personal treatment or prevention plan to manage your risk factors. Follow up as often as recommended to make sure any medical interventions, such blood pressure medication or a statin, are working. Don’t ignore sneaky symptoms. If you have symptoms of heart disease, such as angina (tightness, pressure, or discomfort in your chest when you’re exercising or stressed), see your doctor. Seeking prompt medical treatment can help head off a heart attack. RELATED: Living Well With Heart Disease RELATED: 8 Signs of Heart Changes During Menopause