If we were a normal family, I suppose we’d have a nice bowl of fruit on the coffee table. Instead, the bowl in the den is more likely to be full of old tennis balls, kept there for the odd moment when we decide to take a few into the yard and ask our dog to go fetch. It’s a game he loves more than anything else.

But we don’t play fetch — don’t play at anything at all, really — as much as we should. Our daughter is in college now, our son in high school. Little hands no longer tug at our sleeves, begging us to fold paper airplanes, or hide-and-go-seek, or serve tea in tiny cups to dolls and stuffed bears gathered around a knee-high table. The big cypress swing set in our backyard, once the center of summer, looks as old and useless as Stonehenge.

This summer’s house was a mostly quiet house, weekend afternoons sometimes marked by nothing louder than clicking keyboards — my wife on her keyboard as I typed on mine.

But every now and then, regardless of season, a small thud rises from the floor — a single thump, like a shopper testing a melon for ripeness. Our terrier, an old dog who still yearns to feel fully alive, has found a tennis ball and dropped it at our feet, an invitation to go out and play.

If not for the dog, we might pass a week or even a month and not play at all.

And so, as summer slowly surrenders to fall, and the weather cools, and life outside once again becomes more of a pleasure than a penance, think of this as a small public service announcement from your local dog: Go out and play, with no heed to score, time clock or even a firm set of rules. Play for play’s sake — for the fun of following a ball or kite or flying disc wherever it might lead.

If you need a reason to play, then play because it’s good for you, though play done for a reason tends to take the fun out of it.

As this summer started, and the world was publicly worried about war, warming seas and drought, science writer David Kohn took to the opinion pages of The New York Times to worry about something else: American kids are no longer playing enough.

“Twenty years ago, kids in preschool, kindergarten and even first and second grade spent much of their time playing: building with blocks, drawing or creating imaginary worlds, in their own heads or with classmates,” Kohn told readers. “But increasingly, these activities are being abandoned for the teacher-led, didactic instruction typically used in higher grades. In many schools, formal education now starts at age 4 or 5.”

The trend, Kohn argues, is making our children duller, not smarter. If we want our kids to play more, then adults must lead the way. Which is why, in the last light of these last summer days, I’ve been taking my teenage son outside to play catch. Sometimes, God bless him, the dog plays along.

Danny Heitman is on Twitter, @Danny_Heitman.