Amy Downs overcame a near-death experience, lost nearly half her size and is now training for an Ironman

Credit: Amy Downs

After surviving the 1995 Oklahoma City Bombing, Amy Downs made a commitment to change her life.

At the time of the blast, the then 28-year-old bank teller was working in the Federal Building and weighed 355 lbs. An unhappy marriage had led her to seek comfort in food, and her lifestyle was sedentary. But on that day, as she waited more than six hours to be rescued from the rubble, Downs had an epiphany.

“That’s where I had life flashing before my eyes — one big, long, come-to-Jesus meeting,” says Downs, who suffered severe injuries from the blast. “It was, ‘This is it. I’m getting ready to step into eternity and I never lived my life.’ ”

She couldn’t help but reflect on how her size held her back.

“At that point, I thought about what the weight had prevented me from doing,” Downs, now 50, tells PEOPLE. “I had not lived, and I had let relationships fall apart because I was ashamed of how I looked. So I was regretful as far as what the weight had done to me. I thought, if I ever get out, I’ll fix all of these things. I was doing a lot of bargaining with God.”

Credit: Amy Downs

After the bombing, “it took a few years to get some traction,” says Downs, who lost many coworkers and friends in the blast and spent time recovering from her own injuries. “But I just could not shake the idea that I had a second chance to live my life.”

In 2008, she decided to undergo gastric sleeve surgery to help with her weight loss goals. Her surgeon required her to lose 35 lbs. first, which she did by counting calories and eating healthy, smaller portions. In the year after the procedure, Downs dropped 75 lbs. — and then she started working out.

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“I didn’t even know what the inside of a gym looked like,” she says. “When I saw all of those mirrors I wanted to run.” But she stuck with it, eventually finding her comfort zone in the stationary bike. “Once I rode a bicycle, I remembered being a kid again. It was fun.”

She then started riding outside. “It changed my life,” says Downs, who now works in management and lives in Yukon, Oklahoma. “I think it did two things: It burned calories, and when I spent time on a bicycle, it was time I wasn’t in front of a TV eating. It was like a transfer addiction.”

Credit: Amy Downs

She also discovered her passion for races after volunteering at the Oklahoma City Memorial Marathon Run To Remember, an event honoring those killed in the bombing. While handing out medals, Downs explained, “I’m seeing people of all sizes, shapes and nationalities crossing the finish line and it’s amazing. I said, ‘I am going to run in honor of my friends who were killed.’

Credit: FinisherPix

And she did. By the following year she had lost a total of 200 lbs. and completed the memorial marathon. She also added swimming to her exercise regime and began competing in triathalons. “I had a rough start, but there was something in me that said, ‘If I can do this, it’s so symbolic of my life. I’ve been through so much hardship and have had so much adversity and I’ve overcome it,” says Downs, who now runs and bikes with her husband of 4 years, Terry. “I became really good at goal-setting.”

A few weeks ago, Downs, who now stays in the weight range of 155 to 165 lbs., completed her first half-distance Ironman (1.2-mile swim, 56-mile bike ride and a 13.1-mile half marathon), and plans to finish a full one in Tempe, Arizona in November. The race includes a 2.4-mile swim, 112-mile bike ride and a full marathon of 26.2 miles, which Downs will have to finish in under 17 hours to be considered an “Ironman.”

“There is something symbolic about going out and doing these Ironmans and pushing your body, training and crossing that finish line and proving to yourself that you can overcome, and also to use that to encourage other people,” says Downs. “I love that I don’t look like I have an athlete’s body. If you look at me, I look like a middle-aged woman who is still curvy. But other people look at that, and I can’t tell you how many people message me, who are 50 years old, and say, ‘I’m thinking about learning to run,’ because they see me. They see if I can do it, anybody can do it.”