Adrian Peterson cannot be stopped.

Prior to the season, Peterson told STACK that he was on a quest to become the greatest running back who ever lived.

But teams seemed hesitant to give the 33-year-old a shot. Thirty-three is an eternity in running back years, and after nearly 2,600 career carries, how much gas could AP have left in the tank?

It was only after Washington Redskins rookie running back Derrius Guice suffered a season-ending injury in late August that Peterson got his shot. Almost immediately, Redskins head coach Jay Gruden realized that Peterson was no washed-up veteran.

“He’s actually a physical freak,” Gruden told the Associated Press of Peterson shortly after the team had him in for a workout. “Some of the backs we had in here were huffing and puffing, keeling over. He was standing straight up. He could have gone for another two hours.”

Through three games, Peterson has proved the remarkable physical fitness he showed during his tryout was no mirage. He currently ranks third in the NFL in rushing attempts per game (18.7), fifth in total rushing yards (236) and is tied for fourth in rushing touchdowns (3).

Peterson the bell-cow has carried the Redskins to a 2-1 record, as he’s totaled a combined 286 yards from scrimmage and three touchdowns in the team’s two victories. In the latter, Peterson became the oldest running back since 1964 to rush for at least 120 yards and two touchdowns in a game.

Peterson’s Redskins teammates can’t hardly believe their eyes. “He still looks the same. He still has the big play, home run capability,” Redskins linebacker Mason Foster told The Athletic. “It looks like he’s hungrier than ever.”

Chris Thompson, the second-string running back behind AP on the depth chart, echoed that sentiment. “When you talk about running backs in the league, once we hit 30 there’s like a (stigma) that the guy’s lost it or they don’t have it like they used to,” Thompson said. “But Adrian’s a freak.”

It all traces back to the brutal workouts Peterson endures each offseason, where he beats Pro Bowlers 10 years his junior in just about every drill.

“I’ve been blessed with tremendous talent. But on top of that, I don’t want anyone to outwork me,” Peterson says. “The work you put in, you’ll be able to see the reflection of that when you step out on that field.”

But just any “work” won’t do for Peterson. He needs to build lean muscle, destroy fat, achieve superhuman levels of stamina, and attain a body capable of not just surviving the rigors of the NFL, but thriving among them.