Ask a runner why they run and you'll get any number of answers: their heart, their sanity, to stay fit, weight maintenance and, yes, because they love it.

Most runners start up after vowing to lose weight or to stay fit as the signs of aging begin to creep into focus. It's a reluctant jog at first, with lots of walk breaks, followed by completing one slow mile without stopping, followed by that first 5K — until one day: Poof. They're hooked. You're a runner addicted to the high you get after crushing a few miles before work or after a really bad day.

Running and health magazines laud the benefits of slogging it out on the road or treadmill three to four days a week, and physicians have weighed in with their scientific studies. There's plenty of evidence out there suggesting running is, well, really good for you.

So what's stopping you? If you need a little healthy motivation, here are four of the biggest reasons to lace up those Mizunos you just bought at Big Peach and hit the ground ... running.

No. 1: Heart smart

Doctors agree running significantly reduces the risk of developing heart disease and other cardiovascular-related conditions. Not only does running raise overall good cholesterol, it can lower the risk for strokes by keeping diabetes and blood pressure in check (even for those whose blood pressure or risk for diabetes is already on the rise). Running also strengthens the heart muscle and keeps arteries from hardening by maintaining their elasticity.

Don't believe the hype? According to the National Runners' Health Study done by Paul T. Williams, which enlisted over 156,000 runners from 1991 to 2007:

"Runners who exceed government recommendations for aerobic exercise (75 minutes of vigorous exercise per week, equivalent to running about 4.5 to 7.5 miles per week) have a 40 percent lower risk of heart disease and a 40 percent reduced risk of developing high blood pressure."

No. 2: Running — and milk — do the bones good

Let's put this one to rest, shall we? Running does not damage joints or cause brittle bones through repetitive pounding.

Studies like the one Williams has been conducting for the last 25 years have shown there is no link between running and arthritis. In fact, it's a great way to prevent the same through the continued strengthening and conditioning of muscles and ligaments. As you strengthen your muscles, you build up protection around your bones which helps keep osteoporosis at bay.

Running also does more than get the blood pumping: It releases human growth hormones into your system which work to regenerate bone and muscle. This is especially important for women and as they age, as the rate of regeneration slows.

No. 3: Weighing in

There's no denying that raising your heart rate for 30 minutes or more burns calories — but other than breaking out those cross-country skis in the attic, there's only one other cardiovascular exercise which burns the most calories in that half hour: running.

You'll burn 8.5 calories a minute running at a comfortable pace. This is good news for those looking to lose or maintain weight. It's recommended you run a minimum of three days a week for 30 minutes each day in order to kick those pounds to the curb or to keep your waistline trim.

But, as you up your mileage, your body becomes more efficient at burning those calories. This means that while you will shed some pounds for a few months, you will eventually plateau. But simply adding a couple of days of weight training or strengthening classes such as Pilates into your weekly routine will keep your body fit and your weight under control.

A good combination of running and cross-training is vital to a healthy runner. Pro tip: Add a bit of speed work to your runs to get the heart rate up.

No. 4: Run for your sanity

You'll often hear seasoned runners say they need to run regularly to keep the blues away and their heads clear. And they're correct.

The mental health benefits of running are significant — significant enough for mental health professionals to recommend running to those suffering from conditions such as anxiety and depression as part of their overall treatment. Running helps keep the brain active and focused while releasing endorphins.

While running isn't the cure-all for the blues or for diagnosed mental illnesses like depression, it can help relieve symptoms, reduce stress and give you confidence as you watch your body transform. Running at a steady pace can be hypnotic, causing you to get "in the zone" where you are able to think more clearly. Runners claim to solve their problems or come up with their best ideas while out on a run.

As with any new fitness regimen, always get a thorough physical and talk with your doctor about your personal health to build a proper exercise and running program. Avoiding unnecessary injuries is key to happy and healthy running.