Editor's note: CNN Contributor Bob Greene is a bestselling author whose books include "Once Upon a Town: The Miracle of the North Platte Canteen" and "And You Know You Should Be Glad: A True Story of Lifelong Friendship."
(CNN) -- All around the world today, people are in the early hours of trying to keep their New Year's resolutions: Lose that 15 pounds, find that job that will make you happy, move to that city where you've always dreamed of living.
There is one kind of resolution, though, that very few of us will ever be in a position to make.
Somewhere today, someone at the very pinnacle of his or her career is thinking of doing in 2012 what Tony La Russa did in 2011:
Get out on top.
Willingly walk away and declare victory.
Leave the table while the dice are still hot.
La Russa was the manager of the St. Louis Cardinals who, within days of guiding his team to victory in the World Series, announced that he was done.
It has never happened before in baseball, according to historians of the sport. No manager before La Russa ever retired in the same calendar year his team won the Series.
Human nature tells us to hang on while success is at its peak. You don't see many CEOs who have just led their corporations to record profits say: I have nothing left to prove. I'm through -- it's been fun.
Who does that, when further riches and accolades await? The inner knowledge that things may never be this good again competes against the thought that cruising speed can be exceedingly comfortable once you've made it to the apex. Who reaches the top of the mountain and then, with the cheers still ringing, decides: No more mountaintops for me?
It happens in sports, once in a great while. Rocky Marciano retired from boxing in 1956 as undefeated heavyweight champion of the world. Jim Brown walked away from professional football after the 1965 season while still the best running back in the sport. They had won the game, literally. They left the field and never looked back.
How difficult is that -- not to look back?
There are two schools of thought, each completely understandable. Consider the Beatles. Then consider Michael Jordan.
In 1970 the Beatles, having accomplished everything, officially disbanded and never again shared a public stage.
Less than a decade after they said goodbye to their fans, I had dinner with Ringo Starr, and asked him about it. He was adamant that the band -- all four were still alive at the time -- had made the right decision, and would stick to it. I told him I'd read that a promoter had offered $45 million for the Beatles to sing together one more time.
"I think it was 50 million," Starr said. "But the thing is, we don't want to do it. We don't want to get together. And if we did want to get together, we could do it ourselves; we wouldn't need anybody from the outside offering us any money. I think these promoters keep coming up with these big money offers just to get their names in the paper. It makes them little heroes for a day."
I told him that there were many people who never got to see the Beatles perform, and yearned for the chance.
Starr shook his head. "A lot of people say, 'I never saw them, and I want to see them just once,' " he said. "Well, I never saw the Beatles, either. I really wish I could have, but unfortunately I was onstage. I would have loved to have been out in the audience and have seen the Beatles. I would have liked to see what all the excitement was about."
But, he said, it was over. For the fans -- and for the musicians -- the memories would have to be enough.
Michael Jordan was a different story. His resolve to stay away for good was short-lived. He missed terribly that which he had loved.
During his first retirement from basketball, the Bulls' management put up a statue of Jordan outside the United Center in Chicago. One night I asked him about it.
"Do I look like a statue to you?" he said.
"I'm not a statue. The whole thing makes me feel very strange. A statue just stands still forever while people stare at it. I'm a person. I'm alive."
I asked if he ever planned to drive by the arena and look at the statue.
"No," he said. "It's not something I have whole lot of interest in doing -- driving out to see myself in front of a building. What am I going to do? Get out of my car and toss coins at myself for luck?
"It's a piece of metal. It's stuck in one place. It doesn't move. I'm a man."
It wasn't overly surprising when Jordan returned to the NBA, and then, after a second retirement, when he did it again. A few months ago, in New York, I unexpectedly ran into him on the sidewalk. As we stood speaking on Lexington Avenue near 50th Street, people catching sight of him did stop and stare almost as if they were looking at a statue. In 2009, in a speech at the Basketball Hall of Fame, Jordan said that he might play again when he was 50. When the audience reacted as if it was a joke, Jordan said: "Oh, don't laugh. Never say never."
Next month, he turns 49.
The Beatles stuck to their vow, and now, with John Lennon and George Harrison long dead, the vow is destined to last forever. Jordan? It doesn't seem likely that he'll un-retire one more time, however briefly, to prove something to himself, but stranger things have happened.
Happy new year to the rest of us. We'll never have a choice like that. But somewhere in the United States today, someone at the very top of his or her field is almost certainly thinking about it. When you've loved doing something for your whole life, can you wave goodbye to it before you have to? Ask Tony La Russa a year from now. It can be harder than it looks.
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The opinions expressed in this commentary are solely those of Bob Greene.