Peyton Manning is working out in New Orleans with a view to returning for the 2015 season.
The Denver Broncos number 18 wants his 18th season, and as expected, is going through his usual offseason routine of fitness checks and health evaluations.
But Manning, one of the greatest quarterbacks in the league's history, is in danger of hanging on for too long.
It's an affliction that affects just about every sport - elite athletes often don't know when to call it a day. The training routine, the 'buzz' of competition, the changing room camaraderie.
Nothing can prepare you for life outside the NFL when life inside the NFL is all you've known.
But last season Manning looked broken. He ended the season in desperate (by his standards) form, and the Denver Broncos went from Super Bowl contenders to playoff elimination in what seemed like the blink of an eye.
A torn quadricep clearly hindered the QB for the final two weeks, but a comparison of the first and second half of the season shows that his form cratered well before the injury.
Through Week 10 Manning was light outs - 29 TDs to just seven INTs for a 116 passer rating. After Week 10, he threw 11 touchdowns, eight picks and had an 87 passer rating.
Going from a mark that would be NFL-leading to one that put him on par with Kyle Orton and below Mark Sanchez killed the Broncos.
His health will dictate a possible comeback, but at 39, should he return he will be even more vulnerable to season-damaging injuries.
He's working with a 'career extender' in an effort to prove his fitness, but Manning is not Tom Brady. A New York Times profile earlier this season detailed the Patriots' quarterback's rigorous training schedule.
It's a schedule that is specifically tailored year round to extend his career. Brady's 'body coach', Alex Guerrero controls his entire NFL life - diet, training, recovery, he's even Brady's spiritual advisor and godfather to his son.
Brady and Manning have been compared throughout their careers, and it was difficult to avoid drawing parallels between the two as the 2014 season climaxed.
As the New York Times said: "Brady is bent on nothing less than subverting the standard expectations of how long a superstar quarterback can play like one."
The comparison does not suggest that Manning is not, but serves to underline the total commitment required to keep a body functioning at elite level as age 40 approaches.
Manning, while handicapped by an injury towards the tail end of the season, was a shadow of his former self. For the first time, he looked his age on the field.
He was chewed up in a defeat to the Rams, and ineffective against the Colts in a damaging home playoff defeat. Before that, the Broncos won in spite of his zero TD, two-pick performance against the Bills in Week 14.
An exceptional rushing game from CJ Anderson could not bail him out against the Bengals in Week 16 and the Broncos put up 47 points in the regular season's final game against the Raiders yet Manning didn't have a touchdown.
The warning signs were there before the playoff disappointment.
His passes wobbled as though they were unsure of their destination, his arm strength more Alex Smith than Cam Newton.
His deep ball sailed on him, his fabled accuracy was off.
It's never smart to discount a legendary NFL player, just look what Brady did months after many questioned his future in New England following the second round selection of Jimmy Garappolo.
Broncos need him
But there's uncertainty in Denver that extends beyond Manning. Wes Welker, Demaryius Thomas and Julius Thomas are all free agents. And there's a new coach in town after John Fox was fired.
It's very possible that Manning could have less weapons in 2015, not more, as the Broncos approach a season that looks a lot like a transitional one.
This franchise is loaded with expensive acquisitions like Aqib Talib, DeMarcus Ware and TJ Ward, players brought in to maximise Manning's window.
And this is the elephant in the room for the Broncos. John Elway has constructed a roster completely reliant upon Manning returning for one more year.
They would save a ton of money if he retired (he's to make $19m in 2015 and the Broncos would save $16.5m in cap space) but there is no succession plan in place. Brock Osweiler has been given next to no reps, much to his own frustration…
Losing Manning turns Denver from a free agent destination into an after thought. Elway and team president Joe Ellis need him to return to justify their moves.
The free agent quarterback class is thin, Mark Sanchez, Brian Hoyer and Jake Locker anyone? The Broncos pick 28th in this year's draft, but the top talent will be long gone. The best they could hope for is a latter round development project like Brett Hundley.
The Broncos aren't built for that kind of transition, so it's Manning or bust.
Manning will listen to nothing but his own body. He will talk with Ellis and Elway before the Scouting Combine in Indianapolis later this month, when his intention should become clearer.
The NFL is a physical game, even a quarterback like Manning that never relied on his mobility will eventually find it catching up with him. The second half of last season looked like it finally had.
After the regular season, he publicly admitted that he's unsure if his body is up to a 16-game campaign.
“I’m kind of still determining that. I’m taking some time to assess some things and to see,” Manning said. “Of course I think that’s something that’s important to me is not whether I can physically do it for myself, can I physically do it to help the team? I’ve always wanted to be part of the solution to helping and never a problem.”
Maybe his Jekyll and Hyde performance is best understood within this context. In limited bursts he remains an elite quarterback, but it is too much to expect this from September to February.
It would be disappointing to see Manning return in 2015, only to regress again when the Broncos need him most.
He has the Super Bowl ring and his place in NFL QB history as one of the best ever, does he really need to put his body - that has gone through four neck surgeries - through the wringer again?
Manning wants that second Super Bowl, something that has only become more difficult as the years pass.
But while competitors like Manning want to win as many rings as possible, sometimes knowing when to walk away is just as important a victory.