Image credit: Courtesy Ashley Donahoo, Caroline Jhingory and Leah Fernandez

At 25 years old and 288 pounds, Ashley Donahoo was depressed.

"I was unhappy with my job, I was unhappy with the direction my life was going, and I had a hard time enjoying the little things that my kids wanted to do," the 27-year-old mother of two from Pace, Fla., said. "My health was failing. My doctor told me that he didn't think I was going to make it to 30 if I kept on [this way]. … It kept getting worse and worse."

Donahoo was concerned, but it was her faithful husband, David, who pushed her on a path to health, starting with a walk around the block.

"His heart was breaking for me," she said. "And he saw how unhappy I was, and he came to me and said, 'We're going to go for a walk.' And I was, like, 'No, we're not.'"

Her husband won that battle, and on the walk, she started thinking about her own choices and future.

"The realization hit me that I made this choice. I made this choice to get where I am right now. So I'm going to start making a different choice," she said. "I put my health and myself on back burner, and I think … it had all caught up to me."

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Like Donahoo, Caroline Jhingory reached a similar eye-opening realization about her weight.

"I looked in the mirror one day and just realized I didn't recognize the person that was staring back at me," said Jhingory, 32, of Washington, D.C.

Jhingory's struggles with her weight began early. At age 8, she weighed 120 pounds. Taunted by her peers, Jhingory was enrolled in a medical weight loss program, but it didn't work because she would sneak junk food like candy bars.

"I found a way to be a food hustler and get whatever food I wanted," she said. "Not only did I spend two decades of my life morbidly obese. I spent two decades of my life being taunted and teased in every environment. I never went to prom. I never had dates. I couldn't ride a roller coaster because the safety bar wouldn't go over my stomach."

Jhingory remained heavy until college, when she tipped the scales at 303 pounds and started feeling self-conscious in her new environment.

"I felt like I had a moment when all these difficult experiences were a huge pause button on my life. I finally said to myself, 'I'm tired of this. I want to have a normal life.'"

Jhingory started walking everywhere. Then, she took up a daily cardio regimen to shed the weight, and she rid her pantry of tempting snack foods she once binged on. Now, ten years later and 149 pounds, she has reclaimed her shape and kept off the weight.

"When I'm on that treadmill I'm thinking about those bad situations but it makes me push harder and go stronger," she said today on "GMA."

Jhingory's amazing transformation, along with Donahoo's and other weight-loss success stories, were spotlighted in the "Half Their Size" feature in the latest issue of People magazine.

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Donahoo cut out the late-night binges on Chinese food and snacks that brought her down and thanks to her strong support system, lost 137 pounds.

"I knew better, but it was a comfort thing," Donahoo said of her late-night junk food runs. "It was what I had control over. I still indulge because it's not about complete deprivation. It's about moderation and changing things …. I have a turkey burger and I have fat-free cheese, those kinds of changes. It's a lifestyle."

She credited her weight loss success to tracking her food and exercise on livestrong.com and running. She has run two 5Ks.

Leah Fernandez of Atlanta, Ga., found herself at 251 pounds after two pregnancies. The baby weight stuck and she tended to eat emotionally.

"I wanted the food," she said. "It made me feel good, and so I ate it."

But the motivation to be there for her children helped her turn it all around.

"Thinking about going out to the park with my kids felt like work to me, you know? And at some point I realized that's ridiculous. Not only am I cheating myself but I'm cheating my kids of me," she said.

Fernandez was close to reaching her weight loss goal when tragedy struck.

"I got the news one morning that my husband was killed in a tragic motorcycle accident coming home from work. Just the day before we'd completed our first 5K together, which was a very significant moment in my life," she said today. "He lived passionately and so I continue to honor his legacy and to help my kids."

Fernandez turned to Jenny Craig in March 2011 and hasn't looked back. Since then, she has lost half her weight by staying active with her kids and incorporating walking into her lifestyle.

"I'm getting my groove back. Leah's getting her groove back," she said. "Life today is amazing. It renders me speechless, honestly. I have energy. I have vitality of life. I take things on without fear now."

Watch the full story on "20/20: Half Their Size" Friday at 10 p.m. ET on ABC.