Find a gym with childcare.When our daughter was 17 months old, my husband and I joined a gym that has babysitting and I only wish we had done it sooner. It wasn't as expensive as I thought it would be (way cheaper than paying for a babysitter to come to my home) and my daughter actually enjoys playing with other kids while mom or dad gets a workout.
More: How to Choose a Gym
Break up your runs.Don't assume that you have to run 30 minutes all at once. Take advantage of short amounts of time to run. If you have 15 minutes to run on the treadmill before you start making dinner, go for it. Then, while dinner is cooking, jump on for another 15 minutes. As long as you do the segments in the same day, your body is basically getting the same benefits as if you ran all the miles in one workout.
Make running a priority.Schedule your runs and get your spouse on board so you get help with some of the child-care responsibilities. And get creative by taking advantage of opportunities to run. For example, if you're watching your kid's soccer game, run some laps around the field before or even during the game.
Invest in a jogging stroller.Although it makes your run a little harder, running with a jogging stroller is a great workout and most kids love going along for a ride. Once you a have jogging stroller, you'll find it easier to squeeze in runs. For example, my daughter's preschool is about one mile from our house, so I sometimes run with my two kids in the double stroller and drop her off. (Of course, I do get strange looks from some people on my way back home because I'm running with just one kid in a double stroller.)
Take full advantage of downtime.Parents spend lots of time in the car, shuttling kids back and forth to activities. If you find yourself with a small block of time in between pick-ups and drop-offs, use it for exercise rather than heading home for a very short period of time. It helps to have an extra set of running clothes and running shoes in your car, so you're prepared if you have some unexpected downtime.
More: 6 Tips for Busy Runners