How old is too old? I’m 77 and I don’t know yet. But I will when I get there | Polly Toynbee

HHow old is old? That depends on how old you are, because as you get older you will push that number forward. A recent German study has shown that ‘old’ becomes older as we get older. This question was asked eight times to people over forty. Of course it does. Would Paul McCartney, fit at 81¾, now choose 64 as the time he would need nourishment? Jumpin Jack Flash at 80, he’s as lithe and frisky as ever, but only half Dorian Gray, young in body but a face as soaked as that portrait: is Mick Jagger old yet?

I’m 77: me and my friends think about our age all the time. How old are we exactly? I can feel like Methuselah telling some bright young spark that the first election I covered as a reporter for the Observer was in 1970, or that I remember the old king’s funeral, or that I had a doll ration book (the sweet rationing lasted until 1953), or how the big smog from London of 1952, which killed 4,000 people, I developed bronchitis while breathing in Friars’ Balsam under a towel. That’s old, isn’t it?

But I like to reject the age judgment of others, especially when it comes from trolls on social media. Last week a man posted: “God, are you still here? I thought you had been living in a house for years.’ Another: “Oh, Polly is still alive then?” and a third wrote: “Already retired.” The abuse of enemies mutates from stupid woman to stupid old woman. Even friends, like the honorable one Roy Lilleylast week blogged a compliment (I think), as she reads: ‘She may look like a kind grandmother who makes you fold your pajamas and sit up neatly at the tea table. But… if she was a sports star, she would be a cage fighter.”

When I was 18, I had a (bad) novel published that featured old and boring people in their twenties. Now I think ‘old’ only applies to people who are seriously ill in their brain or body. If you’re alert and flexible, you don’t count as old, right? But certainly not that young. The young people are different, in a different time zone, unencumbered by experiences that curb enthusiasm with, “Oh, we tried that before and it didn’t work.”

At our age you think about death a lot, you calculate how many years you have left, how many Christmases you have left and you wonder whether your youngest grandchild will still remember you. When you look at closets full of clothes, you think: perfectly usable enough to get out of your way, you don’t need anything more, right? And there is no point in wishing to age as beautifully as Helen Mirren; that has never been the case. My generation of wannabe actors in the National Youth Theater will never forget the day they dismissed their foolish delusions as soon as they stepped on stage.

I could boldly say that I’m not afraid of dying, after two brushes with breast cancer: I’m just terrified of dementia or leaving a torture chamber. But I have no idea if that’s true. Until you hear the knock on the door, you can’t know if the philosophical wisdom holds up. I am surprised by the deaths of others, the stoics and the fearful partisans.

You just want to keep going. Blessed with a large, beloved family, four children and seven grandchildren, I often pause to think about my happiness. At my age you have put aside the excruciating youthful worries about how things will turn out. I’m out, and this is as good as I get. I will not improve with age, nor become wiser or kinder. I don’t have a bucket list. Last year I even wrote my memoirs.

If something newsworthy happens to you on the street, you are called “grandmother” or “pensioner”, a meaningless identification as retirees even more socially divided than the rest. The politics of retirees is startlingly contradictory: fewer elderly people are poor than the general population. but it’s still 2 million people. The low-paid are at risk of becoming too sick to work and falling into the gap between benefits and a rising retirement age. Yet the elderly are also the richest; my generation is reaping unearned profits from house price inflation, which is preventing young people from buying. Only 1.6 million retirees has an unmet healthcare need and many die waiting, without any government daring to skim property wealth from the old to fund universal social care. Pensioners are powerful voters, installing one Tory government after another. The young people should wish us all dead, even though polls show them to be astonishingly magnanimous.

Geosciences can keep us alive but clog up NHS beds with multiple miserable morbidities. Could it keep us healthy longer and then kill us quickly? Monday’s historic debate in parliament reflected the two-thirds who want the right to die. Last year, Sima the lab rat became the longest-lived rat in history. What was her sinister elixir? The blood of the young, which revives her organs. By living too long, will we vampire the young? I don’t know how old is too old, but I plan on recognizing it when I get there.