In the suburbs of New Jersey, there is a house that forms an irregular polyhedron. When the home was built in 1977, the woman who was to live there insisted to the builder that the kitchen be this big, the den that, and the closets capacious. The builder patiently explained that if you added up the dimensions of each of these rooms and closets, the number came out to two feet more than the width of the house. My mother would not budge. Thus, to this day, the house looks like something square is trying to escape through its walls.

It's a sunny day last spring, and I am standing at the curb in front of the house and stretching my hamstrings on the bumper of my rental car. My parents sold the property years ago, but I've come back to the area for a family gathering, and with a morning free, I've driven from my hotel across the various parkways and freeways and parking lots of North Jersey to my childhood home. My first steps as a runner were taken there, right there, at the end of the flagstone leading down from the door to where my car is parked. It was a spring morning in 1980; I was 15 and fat and slow and had never run farther than the width of a school gym, trying to escape my tormentors in dodgeball. Over the next three years, I put foot to that square of pavement easily a thousand times, and by the time I left the house for good, at age 18, I had transformed myself into a runner, which I've been, more or less, ever since.

Three decades after that first step, I've come back to rerun my long route.

First, up a short hill, maybe 300 yards, but steep enough to instantly tell me how the run was going to be. I remember charging up this hill with the determined fury of an adolescent, mad at the very idea of gravity, and at the same time I remember wobbling up it unsteadily, practically sobbing with some magnified slight or heartbreak, as teenagers are wont to have. Now I just lope up it, trying to let my 46-year-old legs shake themselves out, and feel nothing more dramatic than a slight cramp.

I turn right, onto Mountain Avenue, once a country road, now a thoroughfare connecting disparate eras of housing development: from our late '70s ticky-tack box to solid '60s ranches to gaudy '90s McMansions. There were days in high school when everything in my life seemed like a Gordian knot, and I had no knife. But then I would run up the hill, turn onto Mountain Avenue, and cleanly solve some miles.

Now, here's my elementary school, a long, one-story building with the kindergarten classrooms at one end and the sixth grade at the other end. I sprint the length of the building, retracing K through six in 90 seconds, then indulge in an unwitnessed home-run trot on the baseball field before moving on. There's my junior high school, two miles from my house, a dreary long walk when I was 12, but today I've run to it in under 16 minutes, and am still breathing easily. I think about the unformed, chubby, spastically awkward kid I was then and take some comfort knowing that at least I'd improved some of my stats.

Next, the town library, which stops me in my well-worn tracks. It was as much a refuge to me as a young boy as the playing fields or woods were to other kids. Amazingly, it has changed very little, and it's easy to imagine that the boy I was is still inside, aged 10 or 11, still pudgy and maladroit, intently reading a science-fiction novel by : Robert Heinlein or Isaac Asimov. It was always far easier for that boy to imagine himself in some faraway world than to navigate the wearying distances of this one. And if he were still inside there, as unchanged as the building around him, and looking out the window, what would he see?

A runner in his 40s, although to the boy, at that age, he'd be simply a grown-up. Bald, like his own father, and stocky, thick through the torso, but fit and shiny with sweat. The boy thinks about how much he gasps and aches and burns when his P.E. teachers force him to run across the gym and back. Standing there the runner seems like part of a different species (despite some unsettling similarities, especially around the nose), and the boy can't imagine what metamorphoses would be necessary to transform his own doughy legs—the ones that rub noisily together in his corduroys—into the running man's delineated quads and calves. The boy says to himself, "Why would anyone ever want to do that?" And he turns back to his book. Outside, the man smiles, shakes off his reverie, and restarts his watch.

Peter Sagal is a 3:09 marathoner and the host of NPRs Wait,Wait, Dont Tell Me! For more, go to.

Peter Sagal is a 3:09 marathoner and the host of NPR's Wait,Wait, Don't Tell Me! For more, go to runnersworld.com/scholar.