Somehow, month after month slipped by as I cared for my baby daughter, Julia, and suddenly it had been two years since I had gone for a run. A jogging stroller, I thought -- that's what I need. I'll take Julia with me.

And so, with visions of myself striding powerfully along wooded trails, I bought a sleek new jogging stroller, took it out on the road and, after years of couch potato torpor, began to run again at last.

For about a block.

I slowed to a walk, completely out of breath. Had motherhood ruined my runs forever?

Not with a more realistic set of expectations, and an understanding that would-be parent-athletes need to start slow. Their bodies must work much harder when they're running or biking for two, according to Lisa Roedersheimer, who recently completed a half-marathon she trained for while jogging regularly with her toddler, Mara.

"Jogging strollers are good, but it gets to be difficult," said Roedersheimer, 27. "You use more energy because usually you're holding onto the stroller with one hand so you're only able to use one of your arms to pump. You don't get the same flow when you're running with one arm."

And of course, there's the added effort of pushing 35 pounds or more of baby and stroller in front of you, often uphill.

For new -- and even not-so-new -- moms and dads, it can be difficult to find time to exercise between changing diapers, preparing meals, cleaning the house, attending play dates, going to work and trying to grab a few hours of sleep now and then. One obvious solution: taking your baby or toddler with you in a jogging stroller, bike trailer or bike seat.

Pediatricians and sports medicine experts say to start slow to prevent injury to both you and your baby. While walking is fine, and even encouraged, as early as a few days after birth, children should have good head control and be able to sit up well -- usually at about six months -- before parents take them running or biking. (And if you're using a bike seat, it's important for them to wear an infant-sized helmet in case of an accident.)

For dad and especially mom, whose body is still healing after giving birth, it's wise to start with walking, experts say. And sometimes, fast walking is plenty of exercise on its own.

Mindy Firman, 34, walks about eight miles each day while pushing a double stroller to drop off her children, 2-year-old Eli and 10-month-old Brian, at day care each morning, and then bring them home again in the afternoon. The walking is low-impact, but she says she definitely feels the burn in her upper body, legs and lungs.

Before she started walking and working out with Cardiomom (www.cardiomom.com), a Pittsburgh fitness group that helps moms exercise while with their young children, she couldn't even lift the double stroller into her car, Firman said. Now she lifts that stroller and pushes it and her two kids -- a combined weight of 75 pounds -- for several miles uphill along Shady Avenue in Squirrel Hill.

"It's definitely heavy, but I think it's the best workout I could get, and it's great because I have my children with me," she said.

Desiree Deli, 29, also started with walking and pushing her daughter, Mila, in a stroller after she gave birth by C-section. Then she began to alternate her pace -- walking for five minutes, running fast for three -- usually three days a week on the relatively flat path that runs along the Allegheny River from Millvale down to PNC Park.

She also works out at the gym three or four days a week while her husband takes care of Mila. The combination of working out, walking and running has gotten her body largely back to its pre-pregnancy shape, and Mila loves the runs -- giggling when her mom runs fast and complaining when she's "just moseying along."

"I don't know that everything is going to go back the way it was completely," said Deli, "but I just feel happier when I'm outside exercising and getting fresh air, and I think it makes Mila happier, too."

Snacks and a full sippy cup for Mila are an important part of every run, Deli said. So is singing songs like "If You're Happy and You Know It" and making occasional stops -- the fountain at PNC Park is a favorite -- to take a break and let Mila stretch her legs, too.

"I don't know how much she's going to love being in the stroller for long periods of time because now she's walking," Deli said, as she guided 13-month-old Mila, who had begun walking a few days earlier, down a hill. "This kid's been walking two days and she's already running."

Roedersheimer said she also started slow when she began training with Mara last October for the half-marathon she ran in March. Although never much of a runner -- she said she "pretty much hated running" after unpleasant experiences in high school and college -- she had agreed to participate in the half-marathon with a friend.

Using a half-marathon training schedule she found online, she began training by running two miles with Mara three times a week, then going for longer runs by herself on the weekends.

Roedersheimer increased her total mileage by no more than 10 percent each week until she was running three miles a day three times per week, and never more than 12 miles on her long weekend runs. Mara was happy to go along, except for the winter day when Roedersheimer "tried to be hardcore," bundling her up in a snowsuit and hat, putting the rain guard on her jogging stroller, and taking her out for a run in the middle of a snowstorm.

Mara cried, which she had never done before, and Roedersheimer had to turn around and go home after little more than a mile.

"I think she was just hot and miserable in that stupid snowsuit," she said.

Now pregnant with her second child, Roedersheimer still takes Mara for walks three times each week despite battling nausea and exhaustion.

Having reached the beginning of her second trimester, she's hoping the morning sickness lifts soon so she can get back to running and even racing. At least for a while.

"I plan to run a 5K every month for as long as possible," she said.