In 2001, Alex Zanardi was racing in the American CART series (similar to F1 but the cars were heavier and had bigger engines). In what was to be his final race, he fought his way from the back of the grid to first place, only to have a huge accident. The nose cone of his car was severed and he lost both legs.
He was fitted with two prosthetic limbs but didn't think they were any good, so he made his own. Two years later he was back racing, using hand-operated controls. He did 13 ceremonial laps of the circuit where he crashed (having crashed with 13 laps to go). According to Wikipedia, those laps times were so quick that, had he been racing that weekend, he'd have qualified in fifth place.
While continuing his racing career, Zanardi also decided to take up handcycling. In 2012 he won gold at the London Paralympics and last Wednesday, on the 15th anniversary of his crash, he won gold at Rio.
Interviewed afterwards, he said: "I feel very lucky. I feel my life is a never-ending privilege."