It's a familiar refrain in homes with teenagers: "Shut off that television, get outside and get some exercise!"
But parents, here's the bad news: If you want your teens to exercise, you need to get out there with them and show how it's done.
"Parents have an incredible, powerful ability to model behavior," says Daniel Kirschenbaum, a professor at Northwestern University Medical School in Chicago and clinical director of Wellspring, which provides treatment services for overweight youths and adults at several U.S. locations.
"You are your own best ally," he says.
Besides being active, parents may need to get creative. And tough. Experts offer a variety of strategies for getting teenagers out for some fresh air.
"Sometimes you have to be a little subtle," says Robyn Spizman, co-author with Evelyn Sacks of "Eat, Nap, Play" (Health Communications, 2010). Even the word "exercise" can induce adolescent eye-rolling, so substitute that word with "adventure," Sacks says.
Or less subtle: Kirschenbaum advises making outdoor family time mandatory, and tying it to allowances.
"It's another thing they have to do, like make their beds," he says. "I'd encourage families to do that — make movement a part of what's required."
The problem is often one of wresting teens away from screens and phones. Teenagers up to age 18 are exposed to nearly 11 hours of media in a typical day, according to a January report by the Kaiser Family Foundation, which several years ago noted high rates of media exposure as a contributing factor to childhood obesity.
Todd Christopher, author of "The Green Hour: A Daily Dose of Nature for Happier, Healthier, Smarter Kids" (Trumpeter Books, 2010), notes that teenagers often use more than one form of media at a time: They may text while watching TV or talk on the phone while using the computer.
Making media part of an interaction with nature can help get teens' attention, he says, citing treasure hunts as an example — either devised by neighborhood parents, or by geocaching and letterboxing. In letterboxing, teens download clues off Internet sites. Geocaching is a higher-tech form of hide and seek, requiring a Global Positioning System into which teens can punch the coordinates of hidden treasure.
Both activities are "a pretense to get outside and have these adventures," says Christopher.
Teenagers may be fearful about changing their sedentary habits. "Emphasize 'getting moving,' " says Spizman.
And don't hesitate to call for backup: Allow the child to bring a friend along on the outdoor adventure.
"They're looking for ways to spend time with their friends," says Spizman, who recommends inviting the friend's family, too.
Other kids may prefer a more private foray into nature. "An introspective and bookish child" may prefer journal writing in a secluded spot, says Christopher. "OK, great. How do we get to this place? Let's get on a bike and take a bike trail."
Kirschenbaum suggests buying an inexpensive pedometer for each member of the family.
"Get one for everybody and have steps become a part of the language of the family," he says. He recommends that families work toward 10,000 steps a day, about 5 miles, which he says is double what most adults walk in a day.
"You start to look forward to ways to get steps. You park farther away" when shopping, for instance, says Kirschenbaum. "Studies show just getting a pedometer and wearing it regularly increases activity."
Besides exercise, many parents want to encourage teenagers to learn about and appreciate nature.
Kelly Dignan of Littleton, Colo., asks each of her two teens to plan a summertime outdoor activity for the family. In years past, they've visited parks, gone fishing and camped with their dad.
"They plan it with my help," Dignan says. "That way they have control over it; it's their idea."
She also asks each child to go on a walk with her at least twice a year. It doesn't sound like much, Dignan says, but it gives her the chance to connect one-on-one with each of them.
"We live near the Platte River," Dignan says. "So we walk and talk and notice the nature. We investigate things up close — like the flowers and all the intricacies each one has."
In their book, Spizman and Sacks call this "the sharing walk."
"They get to talk about whatever they want," says Spizman. "They may want to talk about the latest technological gizmo item that they want. The goal is to, while you're walking, to keep it going, encouraging them to talk about their day — the good and the bad."
Sasha Huffman, 15, of Arvada, Colo., enjoys being with friends outdoors, either biking, walking or sledding.
"When the weather is nice, I (walk) all the time with my friends," she says. "I'd rather talk to them face to face than text them."
Going outdoors with her family isn't so bad, either. In the summer, they spend a lot of time hiking in the nearby mountains.
"I think you gotta kinda try it at first, even if it doesn't sound fun," she says. "At least for me, you enjoy it as time goes by. Then you think, 'Wait, I don't want it to be over.' "
When her adult children were teenagers, Sacks says she often took them hiking, but once at the trailhead she'd hand over the map. "You can put kids pretty darn young in charge," she says. "They have a great sense of direction.
"I just told them 'I'm bringing lunch. You guys take this hiking map and let's go.' At a young age, you empower them."
Use family time outdoors toward building a teenager's talents or hobby interests, advises Spizman.
If you live near the ocean, collect beach glass. If your teen is keen on photography, take a camera and build an album together, or get a photo printed in the high school or community newspaper, she suggests.
Doing anything outdoors has benefits beyond health and wellness. "Families doing this together, really, what you're truly doing is creating these bonds," says Christopher.