GREEN BAY, Wis. -- Mike McCarthy was around the 38-year-old version of Joe Montana with the Kansas City Chiefs in 1994. He coached Brett Favre at age 38 in 2008.

The Green Bay Packers coach knows what an aging quarterback looks like.

He most certainly does not see that in Aaron Rodgers' present. Nor does he see it in Rodgers' future.

Rodgers, 34, has made no secret of his desire to play to age 40 -- and perhaps beyond. The historic contract extension he signed last week -- four years and $134 million added to the two years he had left on his old contract -- takes Rodgers through 2023 season. He will turn 40 on Dec. 2 of that year.

"I think it's very realistic," McCarthy said recently. "Just if you look at his path and particularly just the way he trains and just look at physically -- he's at the peak right now, just the way he moves and his ability to the throw the football. To play the position separately, obviously he's at the top of his game there, too."

In the same breath, McCarthy welcomed any skeptics who would want to question whether Rodgers could maintain his level of play for that long. For McCarthy knows that Rodgers uses anything he can to motivate himself -- whether it was the lack of college offers that forced him to Butte College out of high school or his draft-day slide to No. 24.

"I think it's important for you to write an article that says he can't make it to 40," McCarthy said. "Then he'll play til 45."

Rodgers gets coaches fired

Sunday night's regular-season opener at Lambeau Field against Chicago marks Matt Nagy's first game as a head coach.

It also means Nagy's first look in that capacity at Rodgers.

Don't think the 40-year-old Nagy didn't look at the quarterbacks he'd have to face twice a year in the NFC North before he took the job.

"You, certainly going into this, know the division that you're dealing with and when you have a guy that's one of the greatest all-time quarterbacks that this league has ever had, that's something you need to think about," Nagy said. "But at the same time, that's not going to -- not [just] Aaron but any quarterback -- [it] isn't going to prevent most coaches. I think you're going to trust and if you feel like the situation is right, and so it just happens in my opinion we're in one of the divisions that they have one of the best group of quarterbacks in the division."

It's not out of the question that Rodgers could outlast Nagy -- or even play a part in getting him fired at some point.

Nagy is the Bears' fourth head coach since Rodgers became a starter in 2008. The previous three -- Lovie Smith, Mark Trestman and John Fox -- all were fired. The Lions are also on their fourth head coach since then, and the Vikings are on their third.

California conditioning

The key to Rodgers' 2018 season and beyond could be what he does in the offseason to keep himself young.

Rodgers trains in Southern California. Among his training partners is Packers left tackle David Bakhtiari. Neither Rodgers nor Bakhtiari has yet let anything slip about their latest conditioning practices. Sometimes, Rodgers will offer hints -- such as in 2016, when he revealed that he cut out cheese and other dairy products from his diet.

"He probably does some of those weird diets out in California," said Packers right tackle Bryan Bulaga, who typically trains in Florida. "I don't know what they do out there. All jokes aside, I don't know what they do. I've never really asked that, but I know he and I have our own debates about Florida vs. California, so I don't want to hear about it. But it's impressive every year when he comes back. He's in better shape every year."

Which is why Bulaga believes Rodgers could not play only into his 40s but maintain a high level of play.

"Him saying that, I wouldn't doubt the guy," Bulaga said. "For one, his arm talent is second to none. And I haven't seen any signs of that slowing down from when I came here until now. And second of all is just how smart he is and how intellectual he is and how he understands the game and defenses and how he reads things. I feel like he's always one of those guys that's one step ahead. I feel like he really is. With those two things combined, he takes care of himself really well, especially in the offseason. He never comes back out of shape. I don't see the problem with him saying that."

The first time Rodgers broke his collarbone (2013), he won his second NFL MVP award the next year. Rodgers' position coach last year, Alex Van Pelt, said last season after Rodgers returned from his second broken collarbone but couldn't lead the Packers into the playoffs that "knowing him, it's going to drive him through the offseason."

While Rodgers' collarbone injuries may have been unavoidable, it's the avoidable injuries that his conditioning could help prevent.

"It's about taking care of yourself the right way and eating right and making sure you're getting your massages and doing your body work that's going to hopefully help you avoid some of the soft-tissue injuries," Rodgers said this week. "The major injuries, a lot of them are out of your control. But the other stuff you can control, your sleep schedule, your energy. It's been a little better at that. Hopefully, it carries all 16 weeks and into the playoffs."

No guarantees

The reality of Rodgers' contract is that the Packers could move on after the 2020 season and pick up salary-cap space. It's why you've heard Rodgers say on more than one occasion -- including this week -- that he knows "my future is here for the next three or four years at least, hopefully six or seven and we'll go from there."

Despite nearly $100 million in guaranteed money in the deal, no one can guarantee how it will end for Rodgers.

But if Tom Brady -- and not the likes of Montana and Favre -- is the model at age 41 to follow, then there's reason to think Rodgers can stave off his decline for a while.

"Just in general, you're starting to see some guys play longer," Packers general manager Brian Gutekunst said. "But more than that it's just Aaron's professionalism, the way he takes care of his body, how much it means to him, how important winning championships are, his drive. And then he has a unique talent. So I think, you know, the one thing you can count on from him is he's going to give everything that he's got to be the best he can be and get this team where it needs to be. So I think from that aspect, you know, it's everything we're looking for in a player. We're glad that he's going to be here for the foreseeable future, as long as we can keep him healthy."