There comes a point in every fighter's career where they begin to contemplate walking away from the sport.
For some, it's due to an erosion of talent, an inability to compete at the same level or just a lack of viable challenges.
Others find they have made enough money, proved enough and have a legacy sufficient to no longer threaten their long-term health.
The case for Floyd Mayweather Jr. falls into all of the non-talent related categories. His skills have certainly not eroded yet, though he's reaching an age where it can happen quickly and sometimes overnight.
And that's why 2013 should be his last year in boxing.
It's amazing when you look back and realize that he's been fighting professionally for nearly 17 years already.
In that time frame, he's established himself as an all-time great, regardless of where he goes from here, with as impressive a run of dominance as you'll find in the sport.
His list of wins—Corrales, Castillo, Gatti, De La Hoya, Hatton, Marquez, Mosley, Cotto—is extraordinarily impressive.
He simply has nothing left to prove. And he's beginning to run out of guys to prove it against.
For years the conversation about Mayweather was dominated by the seemingly endless speculation about a bout with fellow pound-for-pound fighter Manny Pacquiao.
The fight has never materialized due to intransigence on the part of both fighters and their camps, and has now definitively passed its expiration date.
Instead, Mayweather will face a 2013 calendar that will seemingly include a matchup at welterweight with Robert Guerrero, and then possibly a career capper with Saul "Canelo" Alvarez at junior middleweight.
Beyond those two fights, there are few viable and sellable-to-the-public bouts available.
Guerrero makes sense, as he currently holds a share of the WBC welterweight title that Mayweather won from Victor Ortiz in September 2011.
He is tough as nails and will make for an exciting, competitive fight. Many have unfairly compared Guerrero with another relatively little-known welterweight champion who wilted under the lights of the big stage.
But Robert Guerrero is no Victor Ortiz. If Ortiz had a fraction of Guerrero's mental toughness, he'd be a much better fighter.
"The Ghost" may not win, but he'll come to, and it wouldn't be surprising to see him take Mayweather through some rough-and-tumble rounds.
A win in this fight would set up what at this point might well be the biggest match in the sport—a showdown with Canelo Alvarez.
It would be the perfect way for Mayweather to end his career: a fight with a young, proud warrior, a fighter who represents the up-and-coming generation versus Floyd's old guard.
The promotion of the fight would virtually sell itself.
New vs. Old. Youth vs. Experience. The possibility of the torch being passed versus a legend solidifying his legacy.
Millions would watch this fight on pay-per-view hoping that somebody finally bests the man they love to hate.
Millions more would watch in the hopes of seeing a legend do his thing one more time and make another elite-level fighter look ordinary.
And no matter how it turns out, this fight should cap a great career.
Short of a bout with Manny Pacquiao, circa 2009, there simply is not, and will not be, a better fight out there. Certainly not one of this magnitude.
Floyd Mayweather Jr. has given everything to the sport of boxing as its premier attraction for nearly a decade.
He's raised the profile of the sport, brought in many new fans and, love him or hate him, generated a buzz unmatched by most fighters in history.
He has his health, his money and his legacy in tact.
With nothing left to prove, and a dwindling list of possible opponents, he should make 2013 count and then call it a career.