CHICAGO — Army veteran Melissa Stockwell has one strong, healthy leg. The other is a scarred, 6-inch stump that she has proudly nicknamed “Little Leg.”

She throws birthday parties for this shortened limb, always dresses it in her favorite colors — red, white and blue — and has trouble imagining going through life any other way. “I’ve done more with one leg than I ever could have with two,” she often says.

The first female soldier to lose a limb in Iraq, Stockwell, 32, has managed to turn a traumatic above-the-knee amputation into an uplifting experience, one that motivates people of all abilities. Since the injury, she has shaken hands with presidents, won three consecutive paratriathlon world championships, run marathons, skied down mountains and raced 267 miles across Alaska in the longest wheelchair and handcycle race in the world.

Last month she declared, “I’m going to be an Ironman,” on her blog and signed up for Ironman Arizona, a punishing 2.4-mile swim and 112-mile bike ride, followed by a 26.2-mile run.

But Stockwell’s physical feats only partly explain why a company like Trek, which ended its relationship with disgraced cyclist Lance Armstrong, now touts her as one of its “great athletes,” calling her an inspirational role model.

Stockwell also empowers others to become more physically active, healthier and socially connected through her work as a prosthetist, fitting amputees in the U.S. and Guatemala with new limbs. In 2011, she co-founded Dare2Tri, a triathlon training group for people with disabilities, where she works as a coach and mentor, often swimming, biking or running alongside her athletes. Stockwell is also an instrumental part of Blade Runners, a running group for amputees, and is active in organizations ranging from the Wounded Warrior Project to the Challenged Athletes Foundation.

“Melissa understands what her role is on the planet,” said her coach, Stacee Seay, national manager for TrainingBible coaching and the head coach for Dare2Tri. “Her injury does not define her, but it certainly, certainly makes her who she is today. She has taken what has happened to her and turned everything about it into a positive.”