"If it is meant to be over, so be it," the injured 41-year-old told a news conference at the Vikings' Minnesota practice facility.
"I am not going to beat myself over it one way or the other," added Favre, who has endured a series of hard hits in what he has said would be his last NFL season.
"I think of it, and I include this year, as 20 great years, good and bad," the former Green Bay Packer said of a career that twice brought him out of retirement to play first for the New York Jets and then the Vikings.
But his record-breaking career may have ended when he got hit during a game against the Buffalo Bills on Dec 5. Numbness in his throwing hand and a shoulder injury have since kept Favre on the sidelines.
"There's no way I would even consider (playing) with those symptoms," he said. "It would be foolish to even think that way."
His injuries, along with the Vikings' decision to put back-up Tarvaris Jackson on injured reserve with a toe injury, have left questions over who will start against the Bears.
Favre, who said he will remain with the team whether he plays or not, would like to see rookie Joe Webb get the call.
"We'll see," interim coach Leslie Frazier told reporters when asked if Webb would be the starter. "Just give it a couple of days.... We'll see what happens."
The other choice would be journeyman Patrick Ramsey, signed by the Vikings on Thursday. But Ramsey has not played in an NFL game since 2008 and his last start came in 2005.
(Writing by Gene Cherry in Salvo, North Carolina. Editing by Steve Ginsburg. To query or comment on this story email firstname.lastname@example.org)