Brian Vickers ignored the first sign something was wrong.
He felt chest pains and shortness of breath, but because the pain was at times less intense than at others, Vickers figured it was something that would go away on its own. Or something that wasn't a big deal.
"I woke up and being young and 26, I thought I was invincible," the NASCAR driver said. "So I just went back to sleep, brushed it off."
Eventually, he had to notice. Vickers suffered from two life-threatening blood clots. Last week he announced he will be out of the No. 83 Red Bull Racing Toyota for the rest of the season. Casey Mears replaced him in the All-Star race.
Vickers is on blood thinners, a potentially dangerous situation if he were to bleed during a race. He plans to return for the 2011 season.
"I can actually race and be on blood thinners. I just can't crash," Vickers said, lightly. "I told them that if I promised not to crash, would they let me race? The answer was no."
A feeling of invincibility isn't unique to Vickers. It's easy to think NASCAR drivers are invincible these days.
Safety advancements have improved to the point where it is nearly impossible for a driver to be hurt seriously in the Car of Tomorrow, especially given the fitness levels of today's drivers.
After all, Carl Edwards' car flipped terrifyingly into the air last year at Talledega, hit a fence, landed on the track and burst into flames, but he hopped out of the car and jogged to the finish line.
Vickers' situation had nothing to do with car safety. It was an unrelated medical condition — one his doctor stopped short of calling rare for a 26-year-old.
Still, it was jarring for his competitors.
"It's just unbelievable to be in a situation where you can't drive a racecar — I can't imagine what that's like to deal with on top of being young, and a fit, young man," Mark Martin said. "It's something that I don't understand yet."
All the drivers got a reminder last week that invincibility is an illusion.