Boston Marathon Race Director's Advice: 'Dream Big'

As a young boy, Dave McGillivray wanted to be a professional athlete, but he was too small to be picked for any teams. His new children's book, "Dream Big," recounts his first Boston Marathon and why he runs every year.

Dave McGillivray, Boston Marathon race director, founder of DMSE Sports which tweets @DMSE. He co-wrote "Dream Big: A True Story of Courage and Determination" with Nancy Feehrer. The book is illustrated by Ron Himler.