not only being the youngest nascar champion but starting in the super bowl of stock car racing, the daytona 500 but a mere six years later he had a halt. i was having numbness and tingling, and started to become short of breath. reporter: suddenly the 26-year-old was in the race of his life. i had a clot in my left leg, an embolism in both lungs and a clot in my left hand. reporter: he was also diagnosed with may them ma s din droem. a battery of tests found something else. a hole in his heart. it was the perfect storm. a hole in his heart, the may thurner syndrome and the cramped quarters of his race car for hours on end. his health and career were at stake.