The only proven way to get a stronger body is making it work harder than it you have in the past.
That works for muscles you can see, such as the biceps or the muscles in your legs.
But it also applies to perhaps the most important muscle in your body -- the heart, which pumps blood through the whole body.
To keep it strong, the heart needs extra work, experts say.
WebMD says that to get benefits such as increased endurance, lower blood pressure, stronger bones and better sleep, most people need to build up to 20 or 30 minutes of consistent activity, three or four times a week.
And activity doesn't mean huffing and puffing as you sweat through a brutal spinning class at the gym. A hard run works, of course, but so does a brisk walk or a bike ride at a bit more than a leisurely pace.
In fact, WebMD says that you can rate your effort on a 0 to 10 scale, with 0 being no effort and 10 meaning going full out. To get the benefits for your heart, you should stay at a 3 to 4, a moderate effort.
Finding Right Heart Rate
If you want to get more precise, you can check your heart rate and work in your target zone.
You can check your resting heart rate and then use a formula found at About.com to learn what heart rate you should seek for the biggest benefits.
But the site also provides a calculator that can give you the range you should work out in to strengthen your heart. (Of course, it is based on a typical person, and could vary based on your genetics and condition.)