Dear Dr. Ken: Every so often, I hear about a guy in his 20s who drops dead of a heart attack. Do I have to worry about my ticker giving out before I'm 40? If I do, it's gonna give me a heart attack. -- Barry H., Denver, Colo.

Barry: So, you're young and healthy and figure heart attacks are something only old guys with beer guts need to worry about? Think again. How you eat, live and exercise now help determine your risk of a heart attack today, ten years from now, and even 30 years from now.

Predicting risk can be difficult, but you have to take into account the major cardiovascular risk factors and fix what you can.

I'm going to list the major things you should be concerned about.

Click to see the big factors.

In Your Control (and fixable)

Cigarette smoking: Quit. If you think smoking cigarettes is cool, you must also think it's cool to slowly kill yourself. (And cigars aren't any safer.) If you need them to relax, get a pet, take a walk, meditate.

Physical inactivity: Get moving. Take the stairs. Leave the car at home and your bus pass on your dresser. Every little bit helps. Even a 20- to 30-minute cardio workout three days a week makes a difference. Lifting weights, while beneficial, isn't enough.

Obesity (a body mass index over 30): Lose weight. Ask your doctor how much, but aim for a BMI less than 25. Click here for an explanation of BMI and to calculate yours.

Trans fats: If you haven't heard of these, wake up and smell the fried food. Not all fats are bad; in fact, some fats such as omega-3 fats (found in fish oils) may help protect your heart. According to recent medical studies, trans fats may be a dietary villain perhaps far worse than "saturated fats" (which may not be as bad as once thought). Trans fats are commonly found in fried food and any cookies or crackers that contain partially hydrogenated oils. Avoid these as much as your willpower allows.

Out of Your Control (Keep your fingers crossed)

Male: Yup, just by virtue of possessing a Y-chromosome, your risk of having a heart attack increases. Apparently, Venus offers a healthier lifestyle than Mars.

Family history of premature heart disease: Having a dad or brother who had heart disease younger than age 55, or a mom or sister diagnosed younger than 65 years old. This is important to know, and an important thing to mention to your doctor. If you do have a family history, then you should be evaluated as early as 20 years of age.

Age: What a drag it is getting old. Just being a male 45 or older puts you at risk. (That stat may be why many people think only older guys have to worry about heart attacks.)

Some Control (Do what you can)

High LDL cholesterol: This is the Bad Cholesterol. This needs to be low. How low depends on a lot of things, so ask your doctor what your number should be. To lower your LDL, you can add fiber -- oats, apples, carrots, etc. to your diet; eat less fatty red meats and more fish and vegetables; be more physically active; lose weight. (If truly needed, there are some very effective medicines your doctor can prescribe.)

Low HDL cholesterol: HDL is the good cholesterol, and the higher the better. You can make it higher with regular physical activity; lose weight; quit smoking. There are also medicines available. See your doctor to find out if your HDL is too low.

Hypertension, aka high blood pressure: The numbers here are important but not as important as this: The lower the better. Losing weight and exercise are two of the best ways to address this

Diabetes: Developing this disease is a result of heredity and/or lifestyle. Nearly 75 percent of people with diabetes die from some cardiovascular-related problem. Staying thin and being physically active can reduce the chance of getting diabetes.

Want to know your risk? Test yourself.

A calculator for cardiovascular disease:
This tool provides an estimate of your chances of having a heart attack in the next ten years.

Remember, a low score only means your risk is low right now. It doesn't mean you'll be safe forever.

Heart attacks are serious business and worthy of a one-on-one conversation with a physician. (If you don't have a doctor, get one.)

Dr. Ken Spaeth is a physician and Research Fellow at the Harvard School of Public Health. He is also co-author of the "Bioterrorism Sourcebook." You can e-mail him your questions at askdrken@aol.com.