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Garret Heisinger knew something was wrong in the fourth grade.
He started to feel sick. His stomach hurt, his head hurt.
"I didn't really want to do anything," he told ABC10 in a recent interview.
Heisinger's mother, Kelly, said a lot of kids in his class had the flu. Garrett stayed home for a week, which was unlike him, she said.
"He was very tired and really pale," she said.
Kelly Heisinger eventually took Garrett to see his pediatrician. The doctor was concerned about Garrett's symptoms and ordered a blood draw.
"I never dreamed in a million years that he could have something as serious as cancer," Kelly said.
But Kelly Heisinger's worst dreams became a reality when Garrett, only 9 years old, was diagnosed with Leukemia in 2013.
"I didn't really know what it meant," Garrett said, recalling the day he learned of his diagnosis. "I just knew that it was bad and you didn't want to have cancer."
For Kelly, the diagnosis left her in disbelief.
"It was horrible," she said. "[I couldn't believe how] in the world that this cute child, this happy athletic, healthy kid could get cancer."
As the cancer progressed, Garrett's athletic life was put on hold, and he couldn't go to school at risk of catching something as simple as a cold, which could've been deadly to his compromised immune system.
"I just had to say good-bye to my friends for a few years," Garrett said. "It was just kind of a big chapter in my life just changed and I couldn't really do any of the things that a fourth-grader kid would want to do."
Despite the seriousness of his illness, Garrett would never question whether he'd beat the disease.
"I wouldn't ask [my mom] because I knew we would get through it," Garrett said. "We're strong people and I knew we ad the strength to get through it."
Garrett recently celebrated the five-year anniversary of his diagnosis. The cancer's run its course, and he beat it.
"[The experience] opened up so many new opportunities for me to just help the world...so other people don't have to go through what I went through," Garrett said.
Kelly said Garrett's goal now is to find a cure for Leukemia.
"He doesn't want kids to have to lose three and a half years of their prime little league time and sports time," she said. "He wants kids to just be kids."
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