ENGLEWOOD, Colo. — As Peyton Manning considers whether to take the gold watch or make one more run at the silver trophy, there are many factors he’s weighing: age, desire, vitality, security, relationships.

General manager John Elway said “the bottom line is we want him back.” So, he asked Manning not to make up his mind until next month after he’s had time to process everything.

Back in September, Manning said he liked Tom Brady’s “When I suck, I’ll retire” quote.

“That’s a pretty good rule,” Manning said on the eve of a season that was filled with fun (planning his own prank after breaking Brett Favre’s touchdown record) and frustration (another first-round flop in the playoffs after a nagging thigh injury).

He’s surely pondering whether an 18th NFL season would look more like the first half of 2014, when a sixth MVP award seemed to await, or the second half, when he struggled to find rhythm and receivers alike.

“If he decides to come back, he’ll give everything he has because that’s the kind of competitor he is and the love he has for this game,” teammate Julius Thomas said Monday while promoting the release of the Havoc DLC pack for “Call of Duty: Advanced Warfare.”

“And if he decides his time of running around and getting chased by big guys is over, he’ll have so much to show for it.”

Although the sting of that last loss — 24-13 to the Colts — is sure to linger, NFL Network analyst and Hall of Fame finalist Terrell Davis said he’s sure Manning is looking a lot deeper.

“My gut tells me that he comes back,” Davis said. “But if he comes back just because he didn’t want to go out like this, I don’t know if that’s the right reason. You come back because you love the game, you want to compete, you enjoy working out, you enjoy going to practice.”

Manning has a lot of things to think about as he ponders his future:

NEW FACES: Adam Gase and Manning were the perfect pair in Denver. Two mad scientists who liked to floor the high-octane offense. Now, Gase is in Chicago with John Fox, and Gary Kubiak is the Broncos coach and Rick Dennison his top offensive assistant.

Although Kubiak’s West Coast offense doesn’t at first glance seem to jibe with Manning’s improvisational style, Kubiak said it’s “easy to build a playbook for him.”

Kubiak found it odd discussing the future of a player who’s coming off a season in which he threw 39 TD passes.

“Look what he continues to do. The offense Peyton runs, he’s tremendous at it, back there in the gun controlling the game, controlling the line of scrimmage. Nobody has ever done it better and he’s the master at it,” Kubiak said. “Actually, I’m looking forward to learning that style and that system that he has.”

Manning has successfully adjusted before. The last two times he had a new head coach, he went 14-2 and 13-3.

BETTER PROTECTION: Manning paid a big price for Denver’s trouble-filled offensive line, and Elway said he’ll fix it this offseason like he did the defense a year ago.

Two starters — center Will Montgomery and left guard Orlando Franklin — are among Denver’s dozen unrestricted free agents. The other starters: Ryan Clady, Louis Vasquez and Manny Ramirez will be trying to recapture their old form after substandard seasons.

AGE OR INJURY: Was that fizzling finish an omen or an aberration? Even if Manning determines it was health, not age, to blame, he has to decide if he’s willing to put his body and mind through the grind of another season.

“I could see Peyton going both ways,” Davis said. “There’s no guarantee that if Peyton comes back he’s going to be in any better situation. I think any quarterback or any player would love to walk out on top, that’s the ideal way to walk out of this game. But the reality is that’s not how most of us leave this game.

“And so, that’s really the question that only Peyton can answer: How does he feel right now? And not right now, give him about a month or so and get away from this stuff, detox and heal up, and then start to miss the game, start getting that fire back in his belly.”