Despite the long road to recovery, he's looking forward to getting back to service.
Mathis was a cadet in the JROTC at Beddingfield High School in Wilson where his leaders say he was a Marine in training from day one.
"He had it in his heart to be a Marine," said Sgt. Maj. Walter Singletary.
"We could never get rid of Duncan," said Maj. James Holloway. "Whenever he had a break in other classes, he was here."
Holloway heads up the JROTC at Beddingfield High School along with Singletary.
They say Mathis knew freshman year that he wanted to be a Marine, and even sported the haircut through most of high school.
"He would roll his sleeves up as if he was in the Marine Corps," said Holloway. "Sometimes, I had to calm him down a little bit."
However, it was that commitment and dedication that his mentors say got him through what happened in Afghanistan earlier this month. Mathis was with his unit in an area known for traps and IEDs when he fell down a 50 foot dry well.
"That was very fortunate for him that it was a well that wasn't booby trapped or something like that," said Holloway.
He broke his legs, ankles and an arm but didn't yell in pain to protect his unit's safety.
When the news traveled home, his former teachers were devastated. However, they say this isn't enough to deter the Marine they know from fulfilling his life-long dream.
"Every child I teach, I teach them from the mindset that I'm preparing them to go into the world," said Holloway.
"No doubt he'll bounce back," said Singletary.
Family friends confirm that Mathis is committed to getting back to work with the Marines, but he is facing a long recovery. Right now, he's being treated at Walter Reed with his mother by his side.