GREEN BAY, Wis. – Julius Peppers hasn’t changed much over the years. He’s still the most impressive-looking athlete in most rooms, including the Green Bay Packers' locker room. He still runs with the defensive backs – not with his position group – when he trains. And, oh, does he train.

More than ever.

At age 36 and entering his 15th NFL season, Peppers let everyone in on a little secret about his longevity: The older he gets, the less time off he takes.

“When I was a little younger I could take two, three months off without doing anything,” Peppers said. “Now I can’t do that. I’ve got to stay active.”

"I like to run," Julius Peppers said, "that's my thing." Jonathan Daniel/Getty Images

One way Peppers does that is to train with smaller, faster players. It’s not unusual in the Packers’ offseason program for the coaches to see the 6-foot-7, 287-pound Peppers going for runs with cornerbacks and safeties whom he outweighs by close to 100 pounds.

“I’ve been doing that since college,” Peppers said. “I like to run, that’s my thing. I like to run in the offseason, so if I have a chance to get with those little guys and try to push myself and use one of those guys as a rabbit, I try to jump in there with them and see if I can keep up.”

And he usually does.

“Julius Peppers is ageless,” Packers coach Mike McCarthy said this offseason. “When you see him run and do some of the conditioning stuff that he runs with the DBs, [he’s] just such an impressive, impressive athlete, and the way he keeps himself in great shape.”

Peppers hasn’t taken a practice off during organized team activities, at least not when reporters have been present, and he wouldn’t want one off even if McCarthy offered. Peppers has missed only one Packers practice – Nov. 30 last year – and it wasn’t because of an injury. To hear teammate Clay Matthews tell it, it wasn’t Peppers’ call to take a day of rest heading into a Thursday night game. It’s the only time he has appeared on an injury report since he signed with the Packers before the 2014 season, and he was removed the next day when he returned to practice.

Although Peppers sounded uncertain about his future after last season’s playoff loss at Arizona, his longtime agent, Carl Carey, scoffed at the idea that Peppers was considering retirement. Carey said at the NFL combine in February that there was no end in sight for Peppers.

In his 14 NFL seasons, Peppers has never had an injury that required surgery. And he hasn’t missed a game since he signed a three-year, $26 million deal with the Packers. His last missed game came in 2007 with the Carolina Panthers. His 10.5 sacks last season marked the ninth time he’s hit double digits.

“Sometimes you see him during the year and you forget, I’m not even going to say how old he is, but how long he’s been in the league and his model of consistency,” Matthews said. “He hasn’t had a 20-sack year. He’s always 10 [sacks], 10, 10, ripping them off year after year, and now he’s a handful of sacks away from being in the top five and a surefire Hall of Famer. It’s fun to watch.

“I’m very fortunate to have him on my team and not only learn from what he’s able to do on the field but kind of how he carries himself and how he goes about his business and how he prepares. Even though I’m going into Year 8, you can always take something away from guys who have similar success – actually a lot more success. It’s a good thing we have him on our team, and I’d like to think he’ll continue that success until he wants to call it a career.”

Last season, on the way to 10.5 sacks, Peppers moved into the top 10 on the NFL's career sacks list, with 136. He’s six away from the top five.

At this point, with Peppers still chasing a Super Bowl ring, there’s no indication he plans to slow down.

“I feel like I’m one of these young guys – most days,” Peppers said. “Some days I get up and I feel like an old man. But for the most part I feel pretty good.”