Diane Van Deren is one of the best ultra-runners in the world, and it all started with a seizure. 

For Diane, a charming mother of three, daily life is a struggle. But as soon as she steps outdoors, she's capable of amazing feats. She can run for days on end with no sleep, covering hundreds of miles in extreme conditions. Diane explains how her disability gave rise to such an extraordinary ability, and reporter Mark Phillips heads to Colorado to get to know Diane, and try to figure out what makes her so unstoppable.