At Ford Elementary School outside Atlanta, the kids keep going around in circles. That's just how the teachers and the parents want it.

Before class each morning, about 200 children walk laps in the gym, earning prizes for the amount of distance they cover. Intended to keep early arriving students from sitting around in the hallways, the program also takes aim at today's weight problem among children.

The fitness campaign at the Acworth, Ga., school has become so popular that kids have taken to walking and running during free time with their parents. Lisa Jacobi, whose daughter Olivia takes part in the school's walking program, said parents should take even more steps.

"I'm just amazed at the size of kids now," said Jacobi, who oversees the "Mileage Club" for the school. "The kids who are considered typical today -- when I was growing up, they would have been the heavier kids. I guess it just bothers me that it is accepted so much. We need to be doing something about it."

Health officials say she's right.

"Our nation's young people are, in large measure, inactive, unfit and increasingly overweight," is how the federal Centers for Disease Control and Prevention puts it.

Consider:

• About 16 percent of children are overweight, and that number is rising. Among children age 6 to 10, the percentage of overweight kids more than doubled during a 20-year period ending in 2002. For children age 12 to 19, the overweight rate more than tripled.

• About one-third of high school students do not take part in regular physical activity during a typical week. Even fewer take part in daily gym classes at school, the CDC says.

"I don't think people are really, fully understanding the magnitude of what this means," said Alicia Moag-Stahlberg, executive director for the nonprofit Action for Healthy Kids.

Physical activity helps young people control their weight, reduce blood pressure, lower their risk of diabetes and some kinds of cancer, and gain self-confidence. Exercise is part of a lifestyle of healthy living, along with good nutrition and proper sleep.

This is not just about play time. Getting kids to exercise is about preventing chronic health problems. The habits established early -- good or bad -- often last a lifetime.

A 2006 long-term study, financed by the federal government, shows that physical exercise drops off enormously as children move through their teen years into adulthood.

For example, only 6 percent of white females got no exercise in a typical week when they were adolescents. By the time they were young adults, 46 percent got no exercise. The same eroding pattern was true for males and females across all major racial and ethnic groups.

Yet a lot of parents don't see a problem. Polls shows parents believe that a majority of children are in good or excellent health. And it is parents who set the tone for exercise, particularly as the summer nears and the structure of the school day goes away.

So what can they do?

Experts say the main suggestion for parents is one they apply in their own lives: make exercise fun, not work. Encourage kids to do what they like to do: soccer, dancing, swimming, jumping rope, skating, even navigating an obstacle course in the backyard.

"If many parents would just go back to the future and think about what life was like when they were children -- from hopscotch to the adventure of climbing trees -- it would go a long way toward promoting more physical activity by their kids," said Cedric Bryant, chief exercise physiologist at the American Council on Exercise.

"If you are going to an amusement park, get a lot of walking in," he added. "If you are taking a winter vacation, go cross-country skiing. As a parent, you just have to do more planning -- you have to look for ways to sneak in pleasurable physical activities."

Society doesn't always make it easy, federal health officials say. Communities are designed to encourage driving, not walking and biking. Safety concerns have limited the times and places for children to play outside. Schools have shrunk the time kids get for exercise.

However, there are also subtle ways for parents to make a child's daily life more active.

Use the stairs instead of the elevator at the shopping mall. Make a family event out of active chores, like raking leaves. Forget driving the kids if a safe walk will do as well.

Giving at least some structure to daily exercise becomes even more important, said Moag-Stahlberg, the leader of the healthy kids coalition.

"As corny as it sounds, it really does mean sitting down with the kids and having a family meeting," she said. "How late can the kids stay in bed? How long can the TV be on? How can a parent find out what's going on? If we don't have the discussion, that's even worse."

Children and adolescents should get in at least one hour of physical activity on most days, if not every day, according to the federal government. That 60-minute bloc per day can be broken into periods for kids -- 10 minutes here, 15 minutes there, Bryant said.

"If you think about it, it's just one hour out of 24," he said. "It really isn't an unreasonable request."

On The Net:

Action for Healthy Kids: http://www.actionforhealthykids.org

American Council on Exercise: http://www.acefitness.org

Centers for Disease Control and Prevention: http://www.cdc.gov

Ford Elementary School: http://www.cobb.k12.ga.us/.875ford/

National PTA: http://www.pta.org/parent-resources.html