This year, he's been fighting his own battle.
Mark grew up playing football and in 2008, he was voted the ACC defensive player of the year. He was also a top prospect for the NFL draft. But that all changed when Mark met his toughest opponent yet, cancer.
"I felt a weakness in my leg and I couldn't run as well as I used to be able to run and then it [his left leg] started to swell," he said.
Mark was diagnosed with Ewing's Sarcoma. It's a rare, but aggressive, bone cancer. Dr. Chip Staddon, a sarcoma expert at Pennsylvania Hospital, says the tumor involved most of Mark's femur, which is the major bone in the thigh.
"Your whole world just kind of stops, like a big echo. I felt like I was in a tunnel when he first told me because I couldn't believe it," Mark's father, Sandy Hezlich, said. For his mother her worst fear was that it was caught too late.
Mark admits his first concern was about football, but then the true scope of his diagnosis sank in. "Am I going to be able to have kids? Am I going to be able to get through the next 6 months?" he said.
But he put those fears aside and decided to tackle the cancer the only way he knew how, head on. He endured months of aggressive chemotherapy and radiation. It may have worn his body down, but never his spirit.
"He was very positive, he knew he was going to do whatever he could to make this go away," his mother Barb Herzlich said.
Fortunately, the cancer had not spread, and the treatments worked. In late November, while still with his team acting as a player coach, Mark announced on ESPN he was cancer-free. "It was great," he said.
He had a rod placed in his bone to help strengthen his leg. He is now also strengthening the hope of other cancer patients.
"Many patients have seen him on television talking about this, about how he got through the treatments and his hope to live a functional life and it's really been very helpful to our other patients," Dr. Staddon said.
Mark is now cleared to begin training again. He's determined to be back running out on the field at Boston College next season.
His father has no doubt Mark will be out there. "It's going to be great, miraculous and it's going to be that way because it's what he wants to do," he said. Mark said, "It will definitely be the biggest accomplishment I've ever gone through in my life."
Mark also said being a survivor comes with a responsibility. He was helped along the way by other cancer survivors and he says he will continue to share his story to help other cancer patients. He has also raised money for sarcoma research which currently gets little funding.
