There is no officially correct way to approach retirement. Some resort to comfortable clichés, such as taking a cruise,redesigning an allotment or binge-eating Werther's Originals between taped episodes of Countdown.
Others recoil at the very notion of ceasing their day job, choosing instead to work on into their twilight years – like David Attenborough or Madonna.
And then there's David Letterman, the US talk show legend, who has gone the underrated third way: letting himself morph into a psychotic, Shoreditch-dwelling Albus Dumbledore.
Recent photographs showed Letterman enjoying his golden years on the Caribbean island of St Barts. Jogging with headphones on, Dave appears with a full white beard, shaven head and lurid yellow shorts, looking on top of the world.
The 69-year-old New Yorker hosted his final show last year after more than 33 years and 6,028 television broadcasts. They were three decades in which Letterman mostly stood before the nation in a sharp suit, clean shaven and with a luscious – if eventually whitening – head of hair.
I've kind of developed a real creepy look with it that I'm sort of enjoying.David Letterman
David Letterman's hair migrated south for the winter. pic.twitter.com/0w4u00fXHS— Charlie Berens (@CharlieBerens) March 23, 2016
Given that stark contrast, his new disguise has shaken up the internet in the way that only a celebrity ageing story can.
Let it go
Yet while the majority of online observers have responded with alarm rather than the callous derision that, say, a woman might receive, the crucial detail in these photographs isn't his facial hair gain (and head hair loss), but underneath it. With a broad smile, famously cranky David Letterman looks ... happy.
It's a maniacal grin, admittedly, but we'll put that down to his being caught by paparazzi mid-stride rather than any slow descent into madness. Letterman has the look of a man finally free to do precisely as he chooses without the pressure of executives, stylists and television critics bearing down on him. He doesn't have to care any more, so he doesn't.
Want further evidence? Here he is speaking to the Whitefish Review on the subject of that very beard, versions of which he has had attached to his face for months:
"You know what? I used to say, every day, 'I am so sick and tired of shaving.' I had to shave every day for 33 years. And even before that when I was working on local TV. And I just thought, the first thing I will do when I am not on TV is stop shaving. And everybody hates it. My wife hates it. My son hates it. But it's interesting. I've kind of developed a real creepy look with it that I'm sort of enjoying. And I can tell that people are off-put by it. And the more people implore me to shave, the stronger my resolve is to not shave."
In good company
Letterman isn't the only man to have left image worries behind in retirement, of course, especially with regards to facial hair – though he may be the finest proponent of post-career image rebellion. Fellow late night veteran Jon Stewart let his stubble grow after finishing the Daily Show last year, for instance; Manchester United legends Roy Keane and Eric Cantona went full-on 'dictator-in-hiding' upon giving up playing; and even dear old Ed Milband looked several leagues chirpier after trading leadership of the Labour Party for a salt-and-pepper beard last summer.
And how can we forget the celebrity faces that fill out, like South American football icons Maradona and Ronaldo or French rugby legend Serge Blanco. Both were once in peak physical condition, now they're entirely unbothered. And why should they be anything else? They've earned a break.
Retirement's about letting go, and David Letterman's doing it right. All hail the psycho hipster Dumbledore. We could all learn a thing or two from him.
The Telegraph, London