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Running is her passion.
The 71-year old grandmother of six ran the grueling race and beat her personal best with a time of 4:25:04, which was good enough to place first in her age group.
"Any time you win your age group in a marathon, it's a huge accomplishment, but especially in Boston, because you have to qualify to be there," Kathy Daniels Communications coordinator for the Chicago Area Runners Association told the Daily Herald.
But this year's Boston Marathon wasn't Schertz' first.
In 2008, the 5' 2", 105 pound woman finished the marathon with a time of 4:40. But she knew she could beat that, she said.
"I've got to come back and do better than that," she said at the time.