(CNN) -- Thought a cold rain and hypothermia were going to stop Mary Shertenlieb from finishing the Boston Marathon? You obviously don't know her.
She's battled and beat cancer -- three times -- after all.
So when she had to stop running the marathon Monday after about 15 miles of it, there was no doubt in her mind she was going to finish.
And finish she did. Several hours after stopping because she was showing signs of hypothermia, Shertenlieb crossed the finish line, with her husband Rich by her side. She was the last person to complete this year's marathon.
"My knees are giving out and Rich was like, 'You've got this, you've got this,'" Shertenlieb told CNN affiliate WHDH.
A steady, cold rain made for a raw, frigid course for runners, and hundreds of them did have to be treated in medical tents for hypothermia.
"They just can't run anymore. They're shivering. They just can't go on," said Wellesley Fire Chief Charles Digiandomenico.
Desiree (Desi) Linden, a two-time Olympian, battled the rain and wind to win the women's division with a time of 2 hours and 39 minutes. She's the first American woman to win the marathon in more than 30 years.
In Shertenleib's case, she had to pause about 15 miles in following doctor's orders.
"At that point, her body began to shiver uncontrollably, her lips turned purple, and because of her compromised immune system, her doctors instructed her to stop running in the rain should this happen," her husband, radio host Rich Shertenlieb, wrote.
But at 8:30 p.m., she started running again, with her husband by her side.
She finally finished the race at 12:18 a.m. Tuesday. People cheered. She hugged her husband. It had been a physically grueling journey. But Shertenleib fought and won -- again.
CNN's Jill Martin contributed to this story.
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