But with his knee gradually regaining its strength and a Feb. 28 date to begin running again, Peterson isn't afraid to be optimistic about when he could play again.
"Right now my goal is to be back by the first, the regular-season opener," Peterson told "The Dan Patrick Show" on Tuesday. "That's my goal."
Peterson underwent ACL surgery on Dec. 30 -- a little more than eight months before the start of the 2012 season. Peterson said he understands that the injury typically requires eight to nine months of rehab, but "right now, I am ahead of schedule."
The Vikings have worked with Peterson to make sure that he's not trying to rush his recovery, and Peterson reiterated Tuesday that he's making an effort to remain patient throughout the process.
"Ultimately, I've got to make sure I am 100 percent before I get back out there," Peterson said. "It's going good so far."