Oksana Masters, Former Ukrainian Orphan Turned U.S. Paralympian, on 'Breaking Society's Molds'

The first time Oksana Masters spotted her image on a massive billboard high above L.A.'s Sunset Boulevard, she wanted to pinch herself.

"It was just insane," the 32-year-old Paralympic superstar, who is currently competing at the Games in Beijing, tells PEOPLE. "In a world where people like me are not made to be seen, it changes everything."

Born with numerous birth defects — which included webbed fingers, six toes on each foot, one kidney and the lack of weight-bearing bones in her legs, all caused by radiation from the 1986 Chernobyl nuclear power plant disaster — Masters was abandoned by her parents as an infant. The first seven years of her life were spent fighting to stay alive in several Ukrainian orphanages.

"I endured a lot of physical, sexual and mental abuse, along with starvation," recalls Masters, who was recently named as one of PEOPLE's Women Changing the World for her work challenging and inspiring others with disabilities.

Her life changed overnight in 1996 after being adopted by an American university professor who not only nursed her back to health — in between surgeries to amputate her legs — but also introduced her to the sport of rowing at 13. "My mom saved my life twice," explains Masters, who quickly blossomed into a gutsy, competitive athlete. "She saved me from Ukraine and saved me by introducing me to sports."

In the years that followed she has emerged as Paralympic icon, winning an array of medals — four golds, three silvers and three bronze in past Winter and Summer Games, and already one gold and one silver in Beijing — in rowing, cross-country skiing, biathlon and cycling. "I just fell in love with the idea that someone like me could represent something so much bigger than myself through sports," she says.

Now Masters, who has written a soon-to-be-released memoir, The Hard Parts, is focused on helping others like her fit in — and succeed.

She works with the nonprofit Kindness Wins to help promote selflessness through sports. And she has also partnered with The Hartford's Ability Equipped Program that, she explains, donates "custom-made adaptive sports equipment to thousands of young kids, helping them live active lifestyles."

Masters describes her ad campaigns for Kim Kardashian's SKIMS shapewear (for which she recently appeared on that billboard in L.A.) and Rihanna's Fenty Beauty cosmetic line as a "big win for representation."

Adds Masters: "Beauty comes in so many different shapes and sizes. Breaking society's molds feels incredible. It's really what motivates me to try and inspire people who society thinks look different and don't fit in."

To learn more about all the Paralympic athletes, visit TeamUSA.org. Watch the Winter Paralympics airing now on NBC.