Dr. Arthur Agatston has some healthy advice for your heart: Mow your lawn yourself.

In his latest book, The South Beach Wake-Up Call, Why America is Still Getting Fatter and Sicker, Agatston, the Miami Beach doctor behind the best-selling South Beach Diet, argues our toxic lifestyle has spawned America’s unhealthiest generation. He calls it “Generation S.” That’s S as in “sick.”

“They were the generation who grew up on junk food and led more sedentary lives,” said the cardiologist. “That lifestyle can lead to heart diseases.”

He’s most concerned with men and women between ages 35 and 44. While the death rates from heart disease have dropped since the 1960s within the general population, they are increasing in the younger age groups — people in their mid-30s and 40s.

“We have made progress in the medical field but if we don’t start changing our eating habits and becoming more active, the medicine alone doesn’t look like it is going to work,’’ said Agatston, the medical director for wellness and prevention for Baptist Health South Florida.

Agatston might just be right. According to the American Heart Association, one-third of American adults are obese and report no aerobic activity. Cardiovascular disease is the leading cause of death in the U.S. and risk factors for heart attacks — diabetes, hypertension, weight — are on the rise.

“It isn’t necessarily that we don’t exercise. It is that we are sitting all the time and technology is making it even easier for us to stay on the couch,” said Agatston, showing images of how the lawn mower evolved to make his point.

“Before, they used to do it with a machete. Then we had to push the mower. Then they invented one for you to sit and drive it. Now it is a robot. You don’t even have to do anything anymore.”

The Calcium Score

One of Agatston’s big issues is how to prevent heart-related illnesses.

“We are doing well with treating people after they have a heart attack, but we are not focusing so much on preventing one in the first place,” he said.

In 1988, Agatston and radiologist Dr. Warren Janowitz developed the Calcium Score, a test that determines the level of calcified plaque that builds up in the coronary and carotid arteries, the arteries that supply oxygenated blood from the heart to the neck and brain (the carotid arteries run through the neck, one on each side). Through a CT heart scan, doctors can determine the extent that plaque particles have lined the inner artery walls, causing the walls to thicken. The plaques can rupture, which can lead to heart attacks.

A diet that’s high in calories, high in processed food and low in nutrients found in fruits and vegetables causes the plaque to build up. A lack of exercise exacerbates the problem.

And doctors often can see the calcified plaque 20 years or so before a heart attack takes place. Hence, the prevention.

“We have been doing this test for nearly two decades,” he said. “It took a little while but it has become widely accepted in our field.”

Agatston recommends that even healthy patients get screened through a CT heart scan and advanced blood test to determine if they have plaque building up in their arteries — especially if there is a history of heart disease in the family.