As human beings age, blood vessels stiffen. The heart has to work a little harder. Bones begin to shrink. Skin becomes less elastic. Eyes lose their ability to focus on objects up close. Muscle mass decreases. Small cellular changes accumulate. Time seems to speed up as the body slows. Athletes notice this process more than most of us do, although some seem to resist it. If you squint at Tom Brady’s head shot for the 2021 N.F.L. season, you might be able to make out a few faint wrinkles around his sturdy brows.

Brady is forty-four. This past season, his twenty-second in the N.F.L., he was the oldest active player in the league by four years. His fifty-three hundred and sixteen regular-season yards gained led the league. So did his four hundred and eighty-five completions and his forty-three touchdown passes. He started at quarterback in four of the past five Super Bowls, winning three. He talked about playing until the age of fifty, or forty-five, or until he couldn’t succeed any longer. But, on Tuesday, before he had reached any of those markers, he announced that he was done. He said that he no longer had the will to make the kind of sacrifices that are required to win at the highest level of football. In the end, it was the enormous time commitment that got old, not Brady.

How did he do it? A few years ago, Brady founded the health-and-wellness company TB12 Sports with his longtime trainer, Alex Guerrero. Apparently, tomatoes were what stood between the hundred-and-ninety-ninth pick in the 2000 N.F.L. draft and immortality. What he needed was escarole and “pliability,” along with an insatiable work ethic and a sizable chip on his shoulder. Of course, the woo-woo wellness stuff—and the associated merchandising—always seemed dubious. (A deeply reported 2015 piece in Boston magazine characterized Guerrero as a “glorified snake-oil salesman.”) But the results were seductive: Brady led his team to the Super Bowl in half the twenty seasons he started. He has more Super Bowl rings by himself than any N.F.L. franchise.

The announcement of his retirement was one of the few things that he seemed, however briefly, unable to control. ESPN reported that Brady was retiring last week. The Twitter account for TB12 appeared to confirm the news, then erased its seeming confirmation. Brady’s father denied the report; Brady’s agent hedged. His team, the Tampa Bay Buccaneers, said they’d yet to hear from him about his exit. On Monday, Brady told Jim Gray that he was still on the fence. But ESPN, in a fit of journalistic integrity, stood by its reporting, and Brady finally made it official on Instagram on Tuesday, thanking pretty much every person in the Bucs organization, while not mentioning the New England Patriots, with whom he won six Super Bowls, at all. (Pettiness, like avocados, has always seemed like a key component of Brady’s program—although, to be fair, he acknowledged Patriots Nation later, on Twitter.)

On the day of his last game, a 30–27 loss to the eventual N.F.C. champion, the Los Angeles Rams, Brady’s performance was eclipsed by the play of two younger quarterbacks, the Buffalo Bills’ Josh Allen and the Kansas City Chiefs’ Patrick Mahomes. Allen and Mahomes are more mobile and athletic than Brady has ever been. And yet, even on that day, Brady just barely relinquished his hold on the N.F.L.’s future, let alone its present. Brady, who is eight years older than the Rams’ head coach, Sean McVay, led his team back from a 27–3 second-half deficit. He threw a fifty-five-yard beauty of a touchdown to close the gap to seven. A nine-yard laser over the middle into a tight window brought his team inside the ten-yard line. That would turn out to be the last pass of his career. The Rams kicked a walk-off field goal, and time ran out.