"When Mark Herzlich first noticed the pain in his left leg, he did what most 21-year-old kids — and the rest of us, too, be honest — would do. He ignored it. He waited for it to go away. He was a football player, after all. A day without pain for a football player is a day they don't try very hard.

"But then," Herzlich said, "it wouldn't go away."

It wasn't a dull ache anymore, either, but a shooting pain. It wasn't going away. And it was impossible to ignore.

"I was naïve," Herzlich said. "And maybe a little scared.""