The phrase "you are as old as you feel" must be one of the most well-used axioms to be found in the dog-eared dictionary of hackneyed expressions – probably because it is as 100% true as it is simple. Yet it doesn't go anywhere near explaining why we feel older or younger at any given time.
This week, though, many people will be rethinking the concept of age thanks to the announcement that middle-age has now been decreed to begin at 55.
"Hurrah!" cry the likes of a million folk like me who are in our 50s… In my case it means I'm only one year into middle-age – which is a wonderful revelation. Because, there was me getting all maudlin about the idea I was approaching the middle of middle-age.
And thinking middle-age was a game of two halves (to quote again from the dictionary of hackneyed phrases) – I was about to train for the final whistle by adopting a sedate walk rather than an enthusiastic sprint.
I was preparing myself for the dignified descent into some distant world of infirmity – bracing myself for a multiplicity of aches and pains – getting ready for an onslaught of dithering combined with that tsunami-made-of-glue which represents slow reaction times.
And now suddenly, out of the blue, I am informed I have only just stopped being officially young. Apparently I am as new to middle-age as some spotty university student is to a more grown-up world during "freshers' week".
Just when I was thinking of looking at a Saga holiday, it turns out I could have been revelling in Club Med thong-clad jollity until just 12 months ago. I'll admit, that's not a pretty thought but – talking of Saga – here's what Emma Soames, editor at large for Saga Magazine, says about the new research which has realigned middle-age: "While historically middle age began at 36, most people now – including the young – no longer think that middle age starts until we are well into our fifties and all felt that being middle aged is in fact a state of mind rather than an age thing – I couldn't agree more."
The research to which she refers was carried out by the Love to Learn online learning website whose director, Gill Jackson, had these words of ageist wisdom: "New middle-agers are active, want to enjoy life and certainly don't see themselves as 'old age pensioners'.
"In fact, our research found that adults in their 50s are overwhelmingly upbeat about the benefits of their age group. They have greater freedom and financial security. More than half said they have more confidence and experience than younger people and are less afraid of making mistakes and a vast majority (87 per cent) have a huge appetite to learn new things and take up new hobbies."
What she doesn't say is that "middle-agers" are generally more cynical – so when we analyse glib words and phrases like "active" and "want to enjoy life" we might want to choke on the Sanatogen which we haven't ever swallowed.
Of course we want to "enjoy life"! What did she think – that we're a bunch of miserable curmudgeons determined to pour cold water on anything and everything that is fun?
Yes, men of my age are more likely to explode with the words: "I don't believe it!" a la One Foot In The Grave – but that's only because we have the worldly wisdom to see how daft a lot of stuff is – like, for example, the supposed revelation that we "have a huge appetite to learn new things and take up new hobbies".
When I was a young journalist I was often brought face to face with the big Styxian subject of Getting Old. In those days cub-reporters were sent out to cover retirement presentations where old geezers who'd worked somewhere for 55 years were being given a gold watch.
"What will you do in your retirement Mr Bloggs?" we'd ask. "Look after the garden – and I might play some bowls," would be the answer. Soon after that, we'd be writing their obituary.
That's when I fell in love with Dylan Thomas's poem Do Not Go Gentle Into That Good Night. "Old age should burn and rage at close of day;
"Rage, rage against the dying of the light."
I adapted it to mean "all age should burn and rage" in the certain knowledge that we only live once and so might as well get on with it and pack everything possible into the one single shot we've got. So this new-found idea about middle-age, for me, just brings more of the same. Grab it, do it and enjoy it to the full.
Grabbing it can result in a few aches, doing everything is getting more exhausting, and enjoying anything is nowadays ring-fenced by dark thoughts of an existentialist nature. Apart from that I am as happy as a sand-boy – as long as I remember to take my blood-pressure pills and get enough sleep.