CORTLAND – Jets nose tackle Damon Harrison felt it before every game last season. He would line up in the tunnel and glance next to him at fellow defensive linemen Muhammad Wilkerson, Sheldon Richardson and Quinton Coples and soak in just how far he’d come.

“Honestly, I think that feeling didn’t go away until probably Week 12. Every week it was the same thing,” Harrison said this week. “It was surreal.”

The three men Harrison lined up next to had all been first-round picks. The Jets defined their roles when they handed in the draft cards. Harrison? He had been stocking shelves at Wal-Mart just a few years prior. Now, he was running out of the tunnel as a starter for the Jets.

Harrison, better known by his nickname “Snacks,” was the surprise star of 2013 for the Jets. He was an unknown entering training camp, but he left with the starting nose tackle spot after Kenrick Ellis went down with an injury.

“I told myself I have an opportunity and I’m not planning on giving the job back to anybody, whether it was Kenrick or a veteran they brought in,” Harrison said. “I knew that was my one shot to solidify myself on the roster. I think I did a pretty good job.”

Uh, yeah.

The stat-driven website Pro Football Focus ranked Harrison as the fourth-best tackle in football in 2013. He solidified the middle of a Jets defense that finished third against the run.

Along with Wilkerson and Richardson, Harrison formed one of the best defensive lines in the NFL. The group became known as the “Sons of Anarchy” — based on the ends of their surnames — and gave Jets fans hope that their defense could be solid for years to come.

This year’s training camp is a much different experience for Harrison than his previous two. In 2012, he was fighting for a roster spot after the Jets signed him as an undrafted free agent out of William Penn, the college he ended up at after a brief stint as an overnight stock boy at a Louisiana Wal-Mart. He made the team, but played very little as a rookie. Last year, he came in fighting Ellis and Antonio Garay for the nose tackle job. This year, he arrives as the established starter, but he said he’s not letting complacency slip in.

“I still have the same mindset I did when I came in my first year as an undrafted guy,” he said. “As cliché as it sounds, I truly feel that way. I don’t feel like I have the job locked up and I just have to get through the season. No, I’m out here every day trying to prove to them why I should remain the starter. There’s nothing different except I know exactly what I need to do now.”

Harrison has spent the beginning of training camp trying to improve as a pass rusher. He only had one sack last season, a number he wants to add to. The defensive line has talked about being the best unit in the league, and Harrison could be a huge part of that.

“I could have done so many things a whole lot better [last year],” Harrison said. “Being young, I didn’t have the experience of seeing things before. I had to learn on the fly. Now I can read blocking schemes and understand other things. What I didn’t do last year I think I’ll do a better job of now.”

The 25-year-old promises he’s not resting on what he did last year. He may no longer be fighting for a roster spot, but he says he’s still fighting.

“I’m still hungry,” Harrison said. “I just have a different appetite.”