Dave McGillivray can tie his accomplishments back to a single life experience.

He saw being too little to be on the basketball and football teams as “the toughest thing that happened to me early on in life, and also, almost the most important.”

A prominent race director, philanthropist, motivational speaker and endurance athlete, McGillivray said that he believes his “best accomplishment is my next.”

Last month, the 63-year-old Medford native completed the World Marathon Challenge—the completion of seven marathons on seven continents in seven days.

“We were all put on earth to give back, help and give forward,” said McGillivray.

That is why he ran the World Marathon Challenge on behalf of Team MR8. McGillivray and Team MR8 raise money to benefit the Martin Richard Foundation, to honor the memory of the 8-year-old victim of the 2013 Boston Marathon bombings.

Competing in the World Marathon Challenge wasn’t the only thing McGillivray has been working on recently—he also co-authored a children’s book.

“Dream Big: A True Story of Courage and Determination” is a nonfiction picture book for readers ages 7 to 10.

The book is based on McGillivray’s 2006 autobiography The Last Pick, in which he shares his own personal story, one of reaching deep and showing extreme determination in the face of doubt, disappointment and loss.

According to McGillivray, the children’s book is the story of how he wasn’t tall enough for basketball or big enough for football. A “burning desire to be an athlete” is why McGillivray opted to try running.

“It drove me to get out of bed, to accomplish,” added McGillivray.

His first marathon attempt was not a success; he did not cross the finish line. Before he crossed the starting line of his first Boston Marathon, McGillivray said he didn’t do much training, which he said explains why he didn’t cross the finish line on that first attempt of the legendary race. He now says that he will only compete if he feels he has “earned the right to do it.”

McGillivray identifies the theme of transference between education and athletics as he was Valedictorian at Medford High School and Merrimack College.

“I never missed school or class or practice at all. For me, I knew I had to show up and work hard every day to succeed,” he said.

At the conclusion of Dream Big, co-authors McGillivray and Nancy Feehrer and illustrator Ron Himler propose a challenge to their young readers.

The “Dream Big” Marathon Challenge encourages young readers to be fit physically, mentally and emotionally by running 26 miles (not all at once), reading 26 books, and performing 26 acts of kindness in 26 weeks.

On March 20, Dream Big was launched at a reception in Boston featuring McGillivray and Feehrer, Scott Middlemiss of the Joseph Middlemiss Big Heart Foundation, Boston Police Commissioner Bill Evans, Boston Athletic Association CEO Tom Grilk, Boston Transportation Department Commissioner Gina Fiandaca, hockey legend Ray Bourque, Bryan Lyons of Team Hoyt, and Tresca Restaurant owner Bill Galatis, who hosted the event attended by friends and supporters.

McGillivray is excited about the book and challenge.

“If someone reads the book and doesn’t do the challenge, then I failed, but if someone does complete the challenge, I have succeeded,” he said.

For details about the “Dream Big” Marathon Challenge, visit