Do you exercise enough? Most people say no, especially in the winter. It is hard to get in the daily recommended 30-45 minutes of good aerobic exercise to help prevent heart disease. But here is the cold, hard truth - sitting too much can kill you.

Every half hour of sedentary behavior per day increases your risk of heart disease. However, any kind of activity can help. A recent study says even a little movement can make a big difference and reduce your risk. The hardest part is getting started, especially if you have been hibernating all winter. But once you flip the switch you will see results; lower blood pressure, weight loss, and feeling better about yourself.

If you need motivation to get started, here it is. Studies show that almost any increase in activity can decrease the chance that you will need a coronary artery bypass or stent.

Exercise does this by beginning an incredible process unique to the heart. We are actually able to grow tiny new blood vessels in our heart muscle, which can then improve its blood supply. The new vessels that develop in response to exercise are called collateral circulation.

Collaterals can provide a bridge around a severely blocked up coronary artery by providing a new source of blood to an area starved of an adequate blood supply. This provides a quasi-auto bypass, giving the effects of bypass surgery without the scars. (Watch the video above to see an example of how collaterals can begin to grow.)

Collaterals develop from aerobic exercise such as walking, running, biking, and swimming. Continuing this exercise for 30-45 minutes per day helps to both recruit and maintain these collaterals. Fortunately, the intensity of your exercise is less important than just doing something; even moving around the house will help. Spring is coming and it's a great chance to get out there and begin an exercise program. Hibernating is not good for the heart!

But can someone exercise too much? The answer is probably yes! Studies suggest that there is an optimal amount to run or exercise. Gentle jogging, if you are able to do it, for even an hour spread out over a week, will help you live longer. But, too much exercise may be harmful. Pheidippides found this out the hard way. He was the Greek runner who ran from Marathon to Athens to bring news of a military victory in the year 490 B.C., shouted the word "Nike" (the winged goddess of victory in Greek mythology) and then collapsed and died of a heart attack at the end of his 25 mile run.

His legacy is our present day marathon, and luckily what happened to him is extremely rare. But, it does look like marathon runners, and other high intensity older athletes, may have a slightly increased cardiac risk than other, less intense exercisers.

So be smart about how much strain you're putting on your body when you're exercising. As long as you're moving, you're helping your heart stay healthy.

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Dr. David Becker is a board certified cardiologist with Chestnut Hill Temple Cardiology in Flourtown, Pa. and has been in practice for 25 years. In 1993, after extensive research, Dr. Becker launched Healthy Change of Heart™, an innovative 10-week program designed to reverse heart disease and improve quality of life through diet, exercise, and stress management. Since then, thousands of patients have participated in the program, achieving significant results in improving cardiac wellness.