When was being old abolished, so that we are all condemned to eternal youth?

I watched a documentary the other night about the life of the stage illusionist "the Amazing Randi". The show looked back at his heady career spent conjuring things up and making them disappear, as well as getting into very small, dangerous spaces – sealed coffins, ice-blocks – and staying until they appeared nearly to kill him. He was also a tormentor of cutlery-bothering charlatan Uri Geller but none of these things was what I gasped at.

The part that made me shriek was news footage of Randi in 1983, shortly after one of his escapology stunts had gone badly awry, putting him in hospital with smashed vertebrae. By this point Randi was white-haired but almost completely bald on top, wild of eyebrow, spindly-limbed, slightly stooped, and dressed in a corduroy suit. Randi had decided to retire from the sort of capers that made him famous. "There comes a time," he said sadly, "when people don't want to see a little old guy getting out of a milk churn." He was 55 years old.

"He's only 55 years old there!" I screamed. "55! Like – 10 years younger than Sting! The same age as George Clooney! The same age as Barack Obama! The same age as the hoards of marathon-running dads who spatter mud over me on Hackney Marshes! The same age as the women who, this very Saturday morning, are tying themselves in double knots down at Hot Yoga!"

But then I remembered that in 1983 people seemed to become old a lot quicker. They were permitted, after the age of about 40, to turn swiftly into fragile, ashen versions of themselves, to start walking with a stick, and to cup their ear and shout, "What? Stop mumbling!" every time a teenager spoke.

Or, in a lot of mothers' cases, circa aged 50 they were given carte blanche to gain 40 pounds, put on a smock with a natty brooch, and stand about at school bring'n'buys flush-faced, with enormous arms like sides of pork loin. This was fine. You'd had your shot at youth. Fresh projects, risk, and making a potential tit of yourself in public was the territory of young herberts.

Now we are supposed to go on and on for ever – transforming, growing, and taking on frightening new challenges. The number of octogenarians rescued each summer by the Lake District Search and Mountain Rescue people attests to this. The fact that Madonna is dealing with her latest family dispute by dressing as a porno-clown and riding a tricycle around the stage while sobbing is some evidence that we have done away with maturity.

My current favourite TV comedy – Grace and Frankie on Netflix – stars in the lead roles Jane Fonda and Lily Tomlin, who are, respectively, 78 and 76 years old. It's not a show about comedic old duffers, it's a show about sexy divorcees in slinky outfits who are discussing the best post-menopausal lubricants. Mashed-up yam, since you ask. You probably didn't.

Fonda, especially, looks eerily neat and vibrant. She is doe-eyed, girlish and wisecracking. But more than this, at a time when, post-40, I have started to feel slightly knackered, Jane Fonda, more than 30 years older than me, has clearly been turning in 18-hour days in a TV studio in order to record 14 half-hour episodes of the show in a row and is signed up for two more seasons.

Being realistic, Fonda could drop dead of old age during this contract while still the height of relevance and would leave behind a waspishly fashionable corpse. Back in 1983 the only parts that a 76-year-old Lily Tomlin equivalent might have hoped to be wheeled out for would be "ghoul", "mummy", or "completely deaf great-great aunty sitting in the back bedroom in 'Allo 'Allo". We have done away with ageing, and I want to think that this is 100 per cent marvellous. But I do wonder if life was simpler, and maybe even better, back when we were allowed a period in which we could stop trying?

I also wonder if today's millennials – much put upon, apparently, with debt, lack of meaningful employment and rampant Instagram-related FOMO – realise that their biggest problems aren't any of these things. Their biggest problem is how much time they've got left. Oceans of time. At least another 70 or 80 years of it. They'll have hair dye, invisible hearing aids, Pilates and spiralisers on their side. They'll have Asos to keep delivering the relevant edgy clothes they need. They'll have the internet to help them keep an eye on youth trends. No comfy chair for the millennial, ever – just decades after decades of lovely time to keep striving and chasing that dream career, along with strong core muscles, the perfect family, and a lovely house to keep it all in.

The Amazing Randi is still alive aged 87. He is "retired", but as far as I can tell is still incredibly busy. He could never have seen how long "being old" would go on. The lazy git. He could have done another 25 years in that milk churn.

@gracedent