It's exhausting to even imagine, but some people actually run the full marathon twice.
They're called Ultra marathoners, or double marathoners, and they get an extra early start. Beginning at 1:30 this morning, then again an hour later, 18 runners unofficially kicked off the Blue Ridge Marathon.
The group is not for the faint of heart. Many of them have trained for years to do this.
One of the participants ran across America and told WDBJ7 before he started, he doesn't care if people call him crazy.
"Crazy is good. Why be normal? This is actually a great event that I'm looking forward to. I love the challenge of what we're about to face, 74 hundred feet elevation change throughout this course," said Jamie Summerlin, a double marathoner.
All these folks ran overnight and joined the official marathoners at 7:35 Saturday morning to run the race all over again.