Adrian Peterson battling lowered expectations with positive mindset

To Adrian Peterson, age is just a number.

The 31-year-old Minnesota Vikings running back has been a dominant force in the NFL since his arrival nine years ago, but as his age increases past 30, expectations from others have taken a hit.

Peterson, who returned from a torn ACL to produce the best season of his career in 2012, said the physical battle with age is nothing compared to the mental game, according to ESPN's Ben Goessling.

"I feel like if you want the best out of yourself, you’re able to mentally get through it and do what it takes," Peterson said. "There’s nothing you can do about (it if) your body starts breaking down and you getting injuries and things like that.

"I mean, there are ways to try and prevent that, but I don’t know what (Walter) Payton did going into his last 1,000-yard season. I don’t know what Emmitt (Smith) did. All I know is that from the history I’ve seen, when it comes to athletes, I’ve (seen) so many athletes go way past what people think. That’s the mindset that I have as well."

Peterson puts himself through an intense offseason workout at O Athletik in Houston in an effort to prolong his high level of performance. He looks to athletes from other sports, like former boxing champ Floyd Mayweather Jr., for motivation to stay competitive.

"It’s a mental battle that we fight." said Peterson. "You know, look at Mayweather. He's beating up on young guys, he's taking them to class, and he’s what - 38, 39? He hasn’t lost a fight. Ever. If he was supposed to listen to people saying, 'You can't. You’re over the hill,' and this, that, and the other thing, then that would control what he was trying to accomplish. He would have several losses on his belt. Whatever someone says about him, you know he has that (zero) in the right place (in his win-loss record)."