The future Hall of Famer says he believes that's entirely possible ... telling TMZ Sports he's gunning to play FOUR more years in the NFL!!

"Man, why not four more years?" AD says. "Why not?!"

Of course, Peterson has never made it a secret he wants to play a whole lot longer than most running backs ever do ... but four more years is a big goal even for him.

Remember, back after the 2018 season, Peterson told us he only wanted to go "maybe two or three more years."

But, when we spoke with the Redskins star tailback over the weekend, he made it clear he wants to carry the rock until he physically can't anymore.

"I don't want to ever be in a position where I look back and say, 'Man, I should have played two more years,'" Peterson says. "'I should of played another year.' I want to enjoy it."

As for why, Adrian says he wants a Super Bowl ring badly ... but Peterson is only about 4,000 yards away from breaking Emmitt Smith's all-time rushing mark.

Seems with four more years of carries ... Emmitt might need to start sweating now??