GREEN BAY, Wis. — Troy Aikman says it's a sure thing: Brett Favre will have second thoughts about hanging up his helmet.

The Hall of Fame quarterback knows how hard it is to walk away from the NFL and never look back. Even after a series of concussions led Aikman to retire from the Dallas Cowboys after the 2000 season, he was tempted to come back two years later.

"I was ready to go and had talked with my wife and everything about it," Aikman said told The Associated Press by phone.

Aikman figures Favre will feel the same pull the closer the 2008 season gets. And he wouldn't be surprised if Favre changes his mind and sends heir apparent Aaron Rodgers back to the bench.

"You want to walk out on top," said Aikman, now an analyst for Fox Sports. "But at the same time, you're walking away from something you really enjoy."

Favre told the Green Bay Packers he was retiring Tuesday, but hasn't addressed the media beyond a brief voice mail to ESPN's Chris Mortensen, citing fatigue as the main reason.

Aikman is looking forward to hearing the three-time MVP fully explain his decision. He wonders if Favre will give himself any wiggle room, similar to Michael Jordan's famous assertion that he was "99.9 percent" sure he was done playing after retiring from the Chicago Bulls in 1999. Jordan, of course, came back to play for the Washington Wizards.

Aikman isn't the only one who expects Favre to question his decision.

"I think he'll definitely have second thoughts, knowing him," former Green Bay Packers coach Mike Sherman said. "He's a creature of habit."

Favre even broached the subject in his conversations with Packers coach Mike McCarthy on Monday night, when he first brought up his intention to retire.

"We talked about the reality that he'll experience," McCarthy said. "And he was telling me about the conversation he'd shared with a family member about when the games start in the fall, it's going to probably hit him the hardest."

But as far as McCarthy is concerned, Favre wasn't waffling.

"I would say that's all speculation," McCarthy said. "Not based on the conversations I've had with Brett."

Packers general manager Ted Thompson said Favre seemed "at peace" with his decision when he made it final in a conversation with Thompson on Tuesday morning.

"But as I've also said, it's a very complicated decision process that he has go to through on this," Thompson said. "I guess you never say never, but I wouldn't anticipate that."

Aikman knows firsthand that retirement isn't necessarily permanent. He fully intended to return to the NFL two years after he retired from the Cowboys, only to have his prospective new team — he won't say which one — pull the plug on the deal at the last minute.

"They were hesitant, for whatever reason, whether it be the health issue, the concussions, or how it would be perceived publicly," Aikman said.

All things considered, Aikman said it was just as well.

"I was glad it didn't work out, in hindsight," he said. "The team didn't have as good a year as I expected."

And perhaps Favre is better off retiring, too.

"When you start giving this much thought to retirement, I think that is a pretty good indicator that it's time," Aikman said.

Sherman, now the coach at Texas A&M, figures Favre will struggle to stay away from football, but eventually will settle into a new routine.

"Once he makes it through that first year, he'll be OK after that," Sherman said.

But what if he doesn't make it that far?

Packers chairman emeritus Bob Harlan said "somebody would find a place for him" if Favre called the Packers in July saying he wanted to play. But Harlan doesn't expect that to happen.

"I would assume he's given this a lot of thought, and I've always felt (wife) Deanna would have a lot to say about it when the time came," Harlan said.

Harlan said it would be a shame to see Favre try a halfhearted comeback similar to that of late Packers defensive end Reggie White. He actually retired three times — once briefly before the 1998 season, once after he changed his mind and played for the Packers in 1998, and then for good after one unremarkable season with Carolina in 2000.

"We've always seen a lot of great, great athletes who decide to try that one more year and it's a disappointment," Harlan said. "I've always felt badly that Reggie came back and played that year at Carolina because he wasn't the same Reggie White. And I think it'd be very sad to see that this wasn't the same Brett Favre. He has been so magnificent. He went out on top: great season, great team record. It's a great way for him to exit and add to his legacy."