I've been running since I was 18 and battling the freshman 15. Worked like a charm to keep the weight off and calm my mind. Now 18 years later, I'm still logging the miles. Take it from me, being a mom doesn't have to slow you down. In fact, running gives me the energy I need to keep up with my two year old.
I like to run solo, but I have connected with a local running group through See Mommy Run. This site lets moms connect with other moms in their area to form running and walking groups. The site takes into account schedules, paces and other details to make the best possible matches. They've got more than 3,000 groups on the road.
Health magazine also has an excellent group called Girls on the Move. Like SMR, they match runners. They offer discounts at stores, running tips and have a great running log.
In addition to forming workout groups, these sites have insightful articles and inspirational stories. They could be just the thing you need to get motivated to stay in shape or start a fitness routine. Need another reason to start? Read Kathleen Zelman's excellent article about the Mother-Daughter Weight Connection on WebMD.