"I knew that if I stopped once I wouldn't have finished," Glass notes.

Bowman says that she was on an "emotional roller coaster" throughout the race.

"There were a couple of miles I'd be on a high, but there would be other miles when I was down and doubted myself," she says.

Bowman says her confidence often corresponded to the amount of people cheering her on. The 15 miles between Wellesley and the infamous Heartbreak Hill, which have relatively fewer onlookers, are particuarly brutal.

"This one woman came up to me before Heartbreak Hill and asked if [the last hill] was it," Bowman says. "I felt terrible telling her no."

Just Do It

Still, the mind games of the race can work in the runner's favor.

"I would stress the mental aspect of knowing that you can do it," Hurley says. "In the last couple miles, finishing becomes an obsession."

Hurley also warns potential runners never to underestimate their abilities. Twenty-six miles may sound intimidating, but, she says, "your body is capable of a lot more than what people think it is."

And, for many runners, the very excitement of the race is what inspires them to push through the final miles.

"I've never felt so utterly supported by total strangers from everywhere," Bowman says.

"There are thousands of people wanting you to finish," Thomas adds. "I wish it were that way with exams and other things in life."