A woman leaves a McDonald's restaurant on the Coney Island boardwalk in the Brooklyn borough of New York City.

Just a fraction of Americans are exercising as much as they're supposed to, costing the health-care system billions of dollars and contributing to people dying early.

Only 26 percent of men, 19 percent of women and 20 percent of adolescents meet the U.S. Department of Health and Human Services' exercise recommendations, according to the agency. Failing to meet the suggested levels of aerobic physical activity adds nearly $117 billion in annual health-care costs and contributes to 10 percent of all premature mortality, HHS said Monday in announcing its latest guidelines.

The data highlight the challenges of persuading Americans to become more active. Between 2015 and 2016, about 93.3 million U.S. adults — nearly 40 percent — were considered obese, as were nearly 1 in 5 children and adolescents ages 6 to 19, according to the Centers for Disease Control and Prevention.

Adults need 150 minutes of moderate to vigorous aerobic activity each week and two days of muscle strengthening activities to stay healthy, and children and adolescents ages 6 to 17 need 60 minutes of moderate to vigorous physical activity every day, HHS says. Most of their time should be spent on aerobic activity but should also include muscle-strengthening and bone-strengthening activities at least three days a week.

Physical activity leads to man immediate and long-term health benefits, the agency said in its updated guidelines.

One round of exercise can reduce anxiety and blood pressure, as well as leading to better sleep and improved insulin sensitivity, the agency said. In the long run, physical activity can improve brain health and reduce the risk for eight types of cancer, fall-related injuries in older adults and excessive weight gain, HHS added.

The agency first published activity guidelines in 2008 to help control the U.S. obesity epidemic. In 2008, the medical costs of obesity were estimated at $147 billion, with costs for people who were obese being $1,429 higher than people of normal weight, according to CDC.

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