Looking at Jenny Hadfield’s trim, well-toned figure, you’d never guess she graduated college 30 pounds overweight. She began running when coworkers talked her into doing a 5K race with them.

“I was beaten by a 72-year-old man. It wasn’t a pretty finish, but it was a finish,” says Chicago-based Hadfield, now 40. “From that point on, I was hooked.”

She eventually graduated to running 10Ks, then half-marathons and marathons. Along the way, she became a coach and author of such books as Running for Mortals.

“I went from struggling to run down the street to running the Boston Marathon,” Hadfield says. “You just never know what kind of runner is inside of you.”

Helping you find the runner within is now part of Hadfield’s regular job as coach of Health’s Girls Gotta Move Running Club, which has convinced more than 27,000 women to hit the road since its launch in April 2006—and no wonder: Running incinerates nearly 700 calories per hour (based on a 150-pound woman going 6 mph), lifts your mood, relieves stress, and lowers your blood pressure. It also boosts your confidence when you set and reach a goal, like doing a 5K or 10K race.

Ready to join the club? Read on for inspiration for your run around the block or that race you want to conquer.

Next page: “It’s a tremendous way to help others.”