Editor's note: Dr. C. Everett Koop was the U.S. surgeon general from 1981 to 1989. He is featured in the recently released documentary film, New York Street Games.
(CNN) -- Here are some statistics to ponder:
-- Thirty percent of third-graders had fewer than 15 minutes of recess a day. (Pediatrics, January 2009).
-- More than 24 percent of U.S. children 2 to 5 are overweight or obese. (Robert Wood Johnson Foundation, December 2009).
-- More than 31 percent of all children in the U.S. are obese or overweight. (Robert Wood Johnson Foundation, January 2010).
When we were kids, we would run home from school, tear through the house, then run outside, screaming goodbye to our mothers before we were even out the door.
For kids who grew up when I did, many years ago, discovering something as simple as an empty lot in Brooklyn was as exciting as if we were Boy Scouts discovering Yellowstone National Park.
We were resourceful, endlessly creative at coming up with games.
At one point we thought: If we were having so much fun playing games on the ground, why couldn't we move it up a few levels? We played the ringolevio (a complex game of tag involving teams) by climbing up fire escapes and that way we could have one game going on, but with kids on all different levels of a building. We played on rooftops constantly, utilizing every space we were able to find.
Being a heavier boy at the time, I was great at Johnny on a Pony (it involved teams climbing on each other's back to get to a goal). I was able to catch my opponents off guard and use my weight to make the other kids fall.
Then came the Spaldeen, the small, pink, high-bounce ball that changed the culture of how the games were played. Street games were never the same after that.
Culturally and morally, street games are so important for our children -- they put kids in situations where they have to put up with others and settle their differences. The lessons you learn playing street games stick with you your entire life and develop character traits that are essential to becoming an adult.
Unstructured playtime, especially outdoors, is one of the most valuable gifts we can give our children. Not only does it give them the physical activity they need, but they learn social skills and life lessons that may later serve them well in a board room.
The negotiations, the compromises, the strategy sessions ... all of this is a part of the games that people have for generations played growing up. Life was once as simple as a stick and a ball, or an old can, or a piece of chalk.
But as important as the social skills that games and playtime can build, the health benefits can be even more consequential. The reasons are at the top of this article. Past generations of kids were simply not routinely obese.
Let your kids go out and play. But you're not going to be able to just tell them, are you? So make your kids go out and play.
Kids ought to grow up playing outdoor games such as stickball, hopscotch, Kick the Can and ringolevio. Now who's out playing in the afternoon? No one.
Turn off the video games, shut down the computer, unplug the television ... and send your children outside for some good old-fashioned fun.
One day they will thank you for it.
The opinions expressed in this commentary are solely those of C. Everett Koop.