By Paul Burton

LITCHFIELD, N.H. (CBS) – Ever since she was a young girl, Caitlin Callinan wanted to run in the Boston Marathon.

“This has been a dream forever for me,” Caitlin said.

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Right now, she’s too young to qualify, but on April 16th she turns 18, and that just happens to be Marathon Monday.

Caitlin Callinan. (WBZ-TV)

“Now that it’s my 18th birthday, I said, ‘That’s my chance.’ It was meant to be,” Caitlin said.

Caitlin will be the youngest official Boston Marathon runner, but she’s not running it for herself.

“I am beyond excited. It’s a huge day especially since I am doing this for my grandfather and for the liver foundation,” Caitlin said.

Caitlin’s grandfather, Wayne Gagne, means the world to this ambitious teen.

“My grandfather has non-alcoholic cirrhosis of the liver, and me and him have always been super close so, and he’s always done so much for me, and I feel like this is my chance to give back to him,” Caitlin said.

Her mother couldn’t be prouder.

“You can’t even describe, she’s amazing. She’s always gone above and beyond. We’re so proud of her,” Jodi Callinan said.

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Caitlin Callinan will be the youngest person running the Boston Marathon. (WBZ-TV)

Caitlin was required to raise at least $6 thousand dollars for the Liver Foundation.

She’s already topped that.

She’s raised $10K and she’s still going.

“I wanted to raise money and spread awareness and just let people know that it’s not just alcohol that can cause the disease, because in his case, it’s not,” Caitlin said. On Saturday she took a quick peak at the finish line.

“It’s very surreal, I’ve always imagined this in my head and I just can’t wait to pass it after those 26.2 miles,” she said.

When she’s done she plans to keep on running in college. She just committed to Saint Anselm.

“She just goes out and gives it 100 percent,” her mother said.

She plans to do the same on Marathon Monday along with her father, Steve Callinan, a NH state trooper, who’s running Cops Kids for cancer.

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“He starts right after me … he will definitely be coming in after me,” she smiled.

Paul Burton