Up until a week before I gave birth to my twin boys, I swam every day. My belly ballooned between the halves of my sports bikini, and the swimmers in the other lanes must have feared that they were going to witness a water birth. I felt weightless and free. The scent of chlorine was bracing yet purifying, and the air bubbles trailed behind me like comets.

I pictured the twins, floating in me as I was floating in the pool. Their eyes closed, their fists clenched, on the verge of unfurling. Did the rocking motion put them to sleep? I hoped that the twins would someday take to the water as easily as I did.

Doctors had to induce labor because I had developed pre-eclampsia, a dangerous rapid rise in blood pressure. I pushed forth one twin and then the next, 26 minutes later. On medication that set my veins afire, I remained dizzy and trapped in bed, on a catheter, with an IV in one arm and a blood pressure monitor on the other.

Back home a couple days later, I walked knock-kneed to the end of our street. “I have to turn around,” I announced. My husband led me back by my elbow.

Week by week, I could go farther and in time, I strapped the twins into the jogging stroller. In the pool, I’d been their boat and now I’d become a sort of pedicab driver. Shielded from sun and wind, the twins didn’t have much of a peripheral view, but they seemed to relish every new sight and sound: the lacy shadows under the sycamore trees or the hip-hop music bumping from a passing car.

At first, the 34-pound stroller weighed more than the babies, but they were getting bigger, and soon I noticed every slope and incline of our neighborhood’s ostensibly flat streets. I was getting stronger, too.

I wanted the twins to see that women – that their mother – could be strong and sure. A body of research suggests that if mothers are physically active and make exercise a priority, so too will their children. When pregnant rats ran on wheels, their pups performed better on a memory test compared with those born to sedentary ones. Another study of a different set of rats found that their offspring are more physically active as adults

After the twins started walking, they squirmed in the confines of the five-point harness, no matter how many snacks, toys and books I piled onto their stroller. I feared our runs were coming to an end.

Before I’d become a parent, I’d been so certain, self-righteous about how I’d raise my children, how they’d eat, sleep and learn, but I’d been humbled. We had to adapt, to be flexible and creative, not only for their development, but for mine, too.

With their growing independence, the twins wanted to roam on their own. I racked my brain for an enclosed space where I could run and they could explore, and came up with a solution: the local tennis courts.

Early in the morning, before the players arrived, before I had to get to work, we headed to a secluded tennis court tucked under oak trees. The twins ran around, played with their Matchbox cars, and ate dry cereal and apple slices while I dashed through laps and intervals. I quickly got over feeling ridiculous about running in the prison yard of my own making.

The twins began to demand those outings. “Mama, Mama, put on your jogging suit!”

If time was short, I ran on our back deck, the boards rattling under my feet while I blasted the stereo with their favorite song on repeat: “Down by the station/early in the morning/see the little puffer bellies all in a row.” The twins raced with their push toys, and chased me around the patio table and chairs until I let them catch me. Then we’d change course and I’d run after them.

They didn’t always cooperate, fighting with each other or attempting to escape. Stop – couldn’t they just stop? I’d frantically do burpees and tuck jumps in a race against their impatience. Sometimes I wanted to run away and disappear for an hour where I could think uninterrupted about my novel or about nothing at all, utterly in the present, the wind against my cheek.

My husband and I tried walks and hikes, but the twins couldn’t go far before we had to carry them.

Just after they turned 4½, the twins rediscovered their scooters, a birthday gift they had long ignored. Seemingly overnight, they gained the strength and balance to ride.

We took them to Lake Merritt in Oakland, an urban treasure with all manner of spectacle on the paved paths: drummers, cavorting capoeira dancers, bubble blowers. We thought they would scooter in circles for a half-hour by the playground and then we’d go home.

They bolted. We ran after them – me in a dress and ballet flats, my husband in jeans and stylish sneakers lacking in any arch support. We called after the twins to slow down, to stay to the right, to watch where they were going, to stop, stop, stop. Each time we caught up, panting and sweating, the boys wanted to continue. Like goldfish set free in a bathtub, the twins wanted to test their new freedom. And so did we.

As we set off, I thought about how much wider the world would now become. We talked about the flat, smooth paths we could try with the twins, along the seashore and through the woods.

But the perimeter of the lake is more than three miles. Eventually the twins faltered, and we’d gone too far to go back the way we came. They perched on our shoulders for a couple hundred yards before my husband and I could stagger no further. They rode their scooters for a few minutes and then whined, “I’m tired.” “Carry me!” The circumference of our future adventures steadily shrank in my imagination.

We limped into a restaurant where we sat at the bar to watch the sunset. A gondola glided by and inky ducks wheeled in the sky while we fortified ourselves with snacks and drinks. Afterward, night had fallen. The twins weren’t often out so late, and never before on their scooters. We flew through the chilly blue-black darkness, the universe expanding once more.