Dr. Christopher Renjilian tells kids to go outside and play. It’s good for their heart, mind, and mood, he says. He is so committed to outdoor time for kids that he helped start a new program called NaturePHL. The program encourages doctors to write real prescriptions— just like they do for medicine—for kids to “run, jump, and explore” in their yard, the woods, or their local park. “We decided to start the program when we realized kids aren’t getting out as often as they should,” says Dr. Renjilian, a pediatrician at Children’s Hospital of Philadelphia (CHOP). He and his CHOP colleagues worked with the Schuylkill Center for Environmental Education, Philadelphia Parks & Recreation, and the U.S. Forest Service to launch the nature prescription program in 2017. Participating doctors at two CHOP medical practices ask kids about their outdoor activity during regular checkups. If kids say they haven’t recently played outside or had much other exercise, the doctors write a nature prescription. Being active is important for your health. Health experts recommend that children exercise 60 minutes every day. But most kids don’t, says Dr. Renjilian, who remembers that he loved to play outside when he was a kid and who now likes to run in Philadelphia city parks. Exercise helps prevent diseases and keeps people fit. For example, since your heart is a muscle, it needs exercise to stay strong. “Every time you exercise you make your heart beat faster, which trains it to be healthy all the time,” he says. But there’s more to the nature prescription than exercise. Just walking near a park or other green space can slow your heartbeat “way down,” which is a sign that you’re relaxed, Dr. Renjilian explains. “You’re better able to pay attention, learn, do better in school, and your mood is better. You’re more likely to smile than cry.” He tells the story of one of his teenaged patients who was very sad and depressed. The boy told Dr. Renjilian that what made him feel better was taking his camera into the Christopher Renjilian Giving kids a healthy dose of nature 18