Not many people survive a fall from a 12th floor window. Josh George did–and when he was just four years old.

That fateful fall from his bedroom window caused George to lose the use of his legs, but it also put him on a path towards discovering just how far—and fast—his arms could take him.

In the years following the accident, George would race around the halls of his rehabilitation center in Delaware as a child, learning to dodge nurses before the coming years taking on the sport of wheelchair racing.

He loves not only the competition, but also the intense training that he puts himself through–even if sometimes he has to take some days off from fear of overtraining.

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“One of my favorite feelings at the end of the day is that pure physical exhaustion — that’s an amazing feeling,” George said. “Psychologically that might convince that you’re doing everything right, but sometimes, especially when you’re recovering from an injury, that’s not what you want.”

George won his first race as a young boy using an ordinary wheelchair. In September, George, will be using a brand-new chair specially constructed by BMW engineers for Team USA wheelchair racers.

“You can immediately tell the responsiveness of the frame: it feels like it’s part of your body,” George said of the new chair, which has a customized seat and a cutting-edge carbon fiber design. In it, he’s hoping to race in the marathon as well as the 400-, 800-, 1500- and 5,000-meter races.

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He’s won five medals over the past three Paralympic Games, but he notes that only one has been gold.

“I’ve been great at taking home bronzes,” he joked. “I’m really hoping that Rio will bring more gold with it.”

To learn more about all Paralympic hopefuls, visit The Paralympics begin September 7.