By Kelly Werthmann

AURORA, Colo. (CBS4) – Just 17 years old, a taekwondo instructor is fighting the toughest battle of his life – cancer.

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“A really big shock,” Isaac Martin said of his diagnosis, “It kind of turned everything around and it wasn’t real at first.”

(credit: CBS)

Martin, who teaches at Stapleton Family Karate, was diagnosed with acute promyelocytic leukemia, a rare and aggressive cancer, in late September.

His family rushed him to Children’s Hospital in Aurora after he developed several lumps on his body and blood blisters in his mouth.

Isaac Martin practices taekwondo. (credit: The Martin Family)

“He went from having a lump on his leg to 15 around his body,” Micah Martin, Isaac’s older brother said, “I never knew cancer grew that quickly.”

For two weeks, Martin laid in a hospital bed receiving chemotherapy treatments four times a day. It was exhausting, grueling and at times very frustrating for the teen.

(credit: The Martin Family)

“The hardest part is not being able to teach and feeling weak because of the chemotherapy,” Martin told CBS4’s Kelly Werthmann, “I just want to be a martial arts instructor. I want to give what I’ve learned to other people.”

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Martin isn’t an ordinary taekwondo instructor – he is what most would consider a prodigy.

At just 10 years old, he heard his first-degree black belt and numerous state championships.

(credit: The Martin Family)

“It’s taught me life skills, gave me confidence,” he said, “It inspired me because I saw teenagers growing up and they were all doing martial arts, too, and I want to give that to other kids.”

Students of all ages now learn from Martin at his brother’s school in Stapleton. Micah said his little brother is one-of-a-kind.

“His level of teaching and martial arts at 17 is way above anything I could’ve ever hoped for for myself,” Micah said, “Instead of being a 17-year-old who chooses to go out and do their own thing, Isaac dedicates his life to helping kids.”

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(credit: CBS)

As soon as Isaac’s students got word of his illness, they made sure to let him know he’s not fighting this battle alone.

“The doctors at Children’s said they’ve never seen somebody get so many visitors in a short amount of time,” Micah said. “He got over 40 visits on day one.”

Students and their families delivered dozens of cards and gifts to their favorite instructor.

Isaac said it’s their words of encouragement and support that keep him smiling through his difficult fight.

(credit: The Martin Family)

“Trying to stay positive and knowing that I’m going to get through this helpful,” Isaac said.

One of his youngest students said taekwondo class is more fun when he is around.

“He’s really nice,” six-year-old Peyton Bisbing said, “I miss him a lot, and it means a lot when he’s here.”

Right now, Isaac is out of the hospital as an outpatient, but still needs chemotherapy daily for the next several months.

His mother, a single parent to ten children after her husband passed away when Isaac was an infant, drives him to the metro area from their home in Conifer every day.

“My mom is awesome,” Isaac said, “She’s helped me through a lot of this, too.”

His family has set up a GoFundMe page with hopes of raising $25,000 for Isaac’s care.

Within just days, friends, students and strangers began donating thousands.

“It just really goes to show you when you have a real, genuine heart for people like Isaac does, people are going to get behind you,” Micah said, “Isaac is a fighter from beginning to end. The way he is dealing with this is unbelievable. We are so grateful for the support.”

Isaac echoed his brother’s gratitude, but made sure to share a message to his students waiting eagerly for his return.

“I really miss them a lot,” Isaac said, “I should be back on the mat pretty soon.”

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Kelly Werthmann joined the CBS4 team as the morning reporter in 2012. After serving as weekend morning anchor, Kelly is now Covering Colorado First for CBS4 News at 10. Connect with Kelly on Facebook or follow her on Twitter @KellyCBS4.