In the back of a kitchen drawer, all my outdated Uptown YWCA membership cards are rubber-banded together. Each photo captures a different look, different time, different hair: short and dark, red and shoulder-length, streaky auburn. The oldest shows a woman with long, dark hair, barely out of college: Hello, girl I used to be. The most recent shows a middle-aged woman with a messy blond bob.

The day the Uptown Y opened — decades ago now — was the day I became a member. It was the first and only gym I’ve ever joined.

The Y holds the invisible ghosts of my past selves. There’s the locker I stood before when I was nine months pregnant and turned to see a gaggle of high-school girls staring at me, some unable to stop laughing at the sheer size of my belly, a kind of fascinated horror in their eyes. There’s the hot tub where that same pregnant me used to dangle her legs while being scolded by staffers who would remind me how easy it is to overheat when you’re pregnant. There’s the Fit Kids Gym (which we privately nicknamed the Sick Kids Gym) where I used to leave my three little kids so I could work out. There’s the huge pool we used to haul them to on steamy Minneapolis summer days so that we could cool off before returning to our un-air-conditioned house.

There’s the stretching mat where I often run into my red-haired friend, the one whose husband was my son’s English teacher. There’s the elevator where little kids beg their stroller-laden parents to let them press the button. There’s the desk behind which a male staffer once said, when he overheard me — the focused and quiet Y member who goes there solo and only to work out — laugh unexpectedly, “Whoa! You really should smile more! It totally changes your look!” At which I, long schooled in womanhood, internally responded, “Has anyone in your life ever told you to smile more?” but outwardly just smiled a weary, polite smile.

There’s the track around which, when it’s too hot or cold or icy outside, I have run, jogged, walked, lunged and interval-ed approximately 3,000 times. There’s the drinking fountain where I have patiently waited behind others and where others have patiently waited behind me. There’s the weight room where, over three years, I once observed in wonder as a young, round, soft woman gradually transformed herself into one of the most muscular people I have ever seen.

She still goes to the Y, and so do I.

There’s the back stairwell where I have many times passed a man who runs up and down for a half-hour at a stretch, half-singing, half-panting along to the music flowing through his earbuds.

And there’s the hallway where, after an absence of months, I once saw a strong and confident woman I’d worked out next to for years walking unsteadily between her two adult sons. Was she recovering from a broken arm or leg, I wondered, and went to say hello. But the look in her eyes, the unrecognition on her face, the protectiveness of her sons, hushed me. Early-onset dementia. Later that day I watched her walking around the track, each son holding an arm. Her body remembered its routines, the comfort and calm of ritualized movement.

I can relate to that. Though I have moved many times, from various apartments to various houses, the Uptown Y, despite much remodeling, changes in policy, additions and subtractions of machines and classes, aerobics to Zumba to spin to body flow, has remained a constant in my life.

In the beginning, when I was new to the Y, I would retrieve my personal chart from a file cabinet, clip it to a clipboard and carry the clipboard and a miniature pencil with me from machine to machine, carefully charting how many repetitions at which weight I had completed. It seemed essential to record my progress, an act that, when I look back, mystifies me. Was I afraid that I wouldn’t reach some mysterious goal if I didn’t write down every increment? Did I not trust my own muscles to show me how hard they were working, how much stronger I was becoming?

When I joined the Y, I was childless and driven and getting up at 4:30 in the morning to write and write, in hopes that someday, somehow, I would write the beautiful book I dreamed of writing. Now, at midlife, children grown, I am still driven. That beautiful book I dream of writing still hovers before me, invisible in the invisible air.

Once, a few years ago when I was leaving the track for the weight room, a man came up to me.

“Are you Alison? The writer?” he said. “My wife and I love your novels.”

I looked at him in surprise — this man I would not have recognized on the street — and thanked him for his kind words. Has he, too, been coming to the Y all these years? Can he, too, measure out his life by the hundreds and thousands of times he has entered the thick cinder-block walls of this building? Over a lifetime, we return to certain places again and again and again. Physical manifestations of how and where we have chosen to spend our lives.

Sometimes I stop and close my eyes and breathe and thank my muscles and bones and blood and brain and heart for all the work it does on my behalf, day in and day out, year in and year out, to keep me alive. How it will keep doing so until the moment I die. How magical our bodies are, and the memories they hold. In those moments, the Uptown Y, mundane building that it is, feels like a sacred place to me, a temple of time and work and love and memory.

Alison McGhee writes novels and books for adults and children. She is a four-time winner of the Minnesota Book Award. “Never Coming Back,” a novel about the fierce and troubled relationship between a mother and daughter, was published last week.