As the lone runner ran along the asphalt trail, my head automatically snapped to look.

I used to be that runner — someone who squeezed in a run nearly every day to take a break from the rest of life and feel the outdoors. I long for those days, especially as crisp September days tick closer to the Medtronic Twin Cities Marathon.

For decades, the 26.2-mile run was a tradition that capped my running season before the snow fell and cross-country skiing began.

It all began when I moved to Duluth as a 20-something and thought running would be something fun to do as I made my home in a new city. The first run out the door wasn’t pretty. I couldn’t muster a mile without heaving what I thought would be my last breaths. Six months later, I joined friends at the start of Grandma’s Marathon.

That was 1981, when we ran in cotton T-shirts. We didn’t have music to plug into our ears or social media to shout out to the world about miles we logged and races we ran.

For more than 35 years, no matter the weather or the place, I slipped into my running shoes and escaped. Stuck writing a story? I ran and composed it in my head only to forget it by the time I showered. Mad at my boss? I ran off the anger, fantasizing about an eloquent rant that I would deliver if I could. Time to clean the bathrooms? Time to run.

As a mother of three daughters, my run often was my alone time until it morphed into special moments and conversations with my daughters, who sometimes biked alongside me. On marathon day they were my cheering section, as they and my husband popped up along the 26.2-mile route to wave signs, shout, “You can do it!” and give me a hug when I did.

Eventually, my daughters put on their own running shoes, outpacing me as they competed in high school, college and beyond. On marathon day, they reined in their speed and ran the last few miles alongside me.

As the years passed and my number of marathon finishes grew, I was at a loss to explain why I continued to run them.

I didn’t run to compete. I never ran a tempo run or fartlek. The only speed work I did was racing to beat a red light at an intersection. I printed out lots of training programs but never followed one. And I never calculated my pace, so my finish times were always a surprise. I didn’t even realize I ran a Boston qualifying time until a friend mentioned it to me months later.

Boston was never really my objective. Besides, I preferred to be cross-country skiing rather than logging long winter training runs for the premier April marathon. I would save Boston for another year. But after decades of running, time ran out.

Eventually I racked up injuries. When I tore both hamstrings, the doc said I might not be able to run long distances again. I did. When a surgeon cleaned up the shredded meniscus in my knee, he counseled: “At your age, you might want to give up long runs and ride a bike instead.”

I stopped listening after he said: “At your age. ” Sheesh. I was only in my early 50s.

As I lined up for my next marathon, the people I used to walk to the start with had given up the 26.2-mile race as knees and hips started to wear out. A few dropped running altogether; others switched to half-marathons and 10-mile races in search of something that took less of a toll on their bodies and far fewer hours of training.

In the minutes before the start gun sounded, I realized that most of those surrounding me were half my age. It’s not that older people don’t run marathons; there are just fewer who do.

Over the next couple of years, a neuroma in my foot hobbled and slowed me. Running was becoming less carefree and easy. But it was my knee that eventually had me saying uncle. I didn’t just stop running marathons, I started taking the elevator instead of the stairs at work. A daily walk made my knee swell. Canoe portages were tough.

When injections no longer kept the pain and swelling at bay, it was time to cut out the old joint and put in a newfangled knee.

My surgeon didn’t say I could run; he just didn’t say I couldn’t. Without long-term studies regarding running and artificial knees, he said most surgeons merely opine that it’s probably not a great thing to do. “You’re an adult,” he said. “You can do what you want.”

Great. That’s what I tell my kids when I know they won’t listen to me.

Nearly three years later, I now walk and bike more. I added a few days of trail running thanks to a physical therapist who works with other runners who have artificial joints. My menopausal body is screaming to get back into shape and run a bit more, but that means I need to get a lot more serious about the exercises my therapist gave me.

My marathon days are over, and I’m OK with that. But it’s difficult to admit I’m not a runner anymore.

It took me months after my surgery before I canceled my subscription to Runner’s World. It was hard to let go of a community I felt I belonged to. But eventually, I couldn’t bear to flip through the glossy pages of runners sprinting to finishes.

When one of the hangers weighted down by race medals fell to the floor in the back of my closet, I left it lie rather than gathering it back up. Maybe I’m still grieving what had been a part of my life for so long. If that’s the case, I need to get over it. I’m not dead.

Cross-country ski season is around the corner, and that will give me an aerobic fix. In the meantime, on the day of the Medtronic Twin Cities Marathon and 10-mile race, I’ll line up at the start because I’m reluctant to let go of a fall tradition.

When the gun goes off for the 10-miler, the racers will run.

I’ll walk.