Leukemia Survivor Celebrates Her 170-Lb. Weight Loss by Indoor Skydiving: 'I Never Want to Stop'

Beyond the Scale rollout
Beyond the Scale rollout

Courtesy; Winnie Au

Maria Castro struggled with weight her entire life, but when she was diagnosed with leukemia in 2007, her weight became a much bigger issue.

She "started packing on weight" while taking her oral chemotherapy medication. And with two young sons at the time and a full-time job as a school teacher, Castro admits she'd "forget to prioritize myself."

"I really was not giving any kind of attention or importance to providing proper nutrition to my body and I didn't do any exercise whatsoever because, at my size, I couldn't physically do so," the 45-year-old tells PEOPLE in this week's 'Beyond the Scale' feature.

It wasn't until years later when her son turned 16 that Castro realized something needed to change in her life.

In 2019, her son asked to go indoor skydiving with friends and family for his 16th birthday party, so Castro made the fun-filled day happen. However, the Bronx native quickly learned that at 328 lbs., she was too big to participate. The skydiving gear didn't even come in her size and Castro was the only one forced to sit out.

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Beyond the Scale rollout
Beyond the Scale rollout

(Photographer) Winnie Au; (Location) iFLY Paramus

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"​​I watched my whole family have this experience I couldn't partake in. I remember sitting outside that glass tube and just being devastated—the shame," she recalls of that eye-opening day. "When you're morbidly obese, you're painfully aware when you walk into any environment, you're the largest person in the room."

The following day, Castro decided to turn to WeightWatchers for help after seeing positive results from her colleagues. In her first moments of the program, she had the words of a coach resonate with her: "This isn't a race. It's a marathon and it's for the rest of your life."

Within a year, Castro learned better nutritional habits and dropped her first 100 lbs., which made it easier for her to be able to exercise regularly for the first time in her life. She admits that her strength and confidence has skyrocketed since embarking on the journey.

Today, Castro — who now weighs 158 lbs. — praises the small victories that she's been able to accomplish after losing the weight.

Beyond the Scale rollout
Beyond the Scale rollout

(Photographer) Winnie Au; (Location) iFLY Paramus

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"Just having enough stamina to be able to walk around the grocery store or the mall with my sons, being able to fit in the backseat of a car with other people, or wearing riding boots that fit around my calves," Castro says. "And I will never get over the excitement of being able to cross my legs when sitting."

"I feel great. I never want to stop," she continues. "My doctor told me that this is the best thing that I could have done for my life and for my health. She admitted to me, 'I was more worried about the weight killing you than the leukemia killing you.'"

Last month, Castro even decided to celebrate her 170-lb. weight loss by making an emotional return to the indoor skydiving facility to participate in the activity that shook her three years ago.

"I feel like this is the most appropriate way to celebrate everything I've been through," she says of her flight. "It's extremely emotional and cathartic for me because it's my journey coming full circle."

For more "Beyond the Scale" stories in this week's PEOPLE, pick up a copy on newsstands now.