In the treacherous depths of middle age, bits of your mortal frame invariably crumble.

My lower right molar, saved by root canal surgery days after I turned 50, finally disintegrated eight years later. The dentist organising a prosthetic replacement assured me: “We guarantee the tooth for 25 years. That should pretty much see you through!’’

“Couldn’t you please,’’ I asked, “guarantee it for 50?’’

Even as someone who’s cheated several near-death experiences, it’s not often I sense the icy spectre of mortality. But I did in the dentist chair. The dentist was dealing with the actuarial facts: given the average Australian male life expectancy of 81.3 years (85.4 for females), the implanted molar would perhaps not only see me through – but also out.

According to the stats I might be almost at three-quarter time.

Even writing this feels jinx-ish. I don’t often consciously contemplate getting – or being – old. So I was slightly bemused to receive from a (somewhat younger) editor an email with the subject line: Piece about men ageing. As in, would that be something I’d be at all interested in writing about? Nah-yeah.

Let me say upfront: as someone fortunate to be on the cusp of a seventh decade, I have never experienced anything remotely like “ageism’’. I neither feel invisible to the more youthful (a common complaint by older people) nor ostracised, discriminated against or ignored. I accept that such discrimination is subjectively experienced – and mostly very gendered. But it’s not something I know.

I still stand on the bus for those I think elderly. I don’t expect anyone to do so for me. I double-take when someone respectfully addresses me “Sir’’ or “Mr’’ (“He was my father,’’ I’m likely to say). That’s the thing about getting pretty old: you know it, and the mirror doesn’t lie, but you don’t always feel it.

To be human is to know that it must all end. But it’s fair to say that realisation left me far colder at 40 than today. Then, I was in a desperate hurry for professional acknowledgment and recognition. I felt the urgent press of time, the need to achieve ever more. The kudos of awards, the affirmation of colleagues in a game that rewards lone-wolf, look-at-me exceptionalism if not creativity, were significant propellants. Family orbited around all of that; my kids were all right until they sometimes, perhaps consequently, weren’t. None of this was about legacy. It was about the burning “now’’ of self-affirmation in the face of the existential.

Posterity, familial and cultural, really matters now. I write more intently as an end in itself, perhaps with a freedom that comes from experience. Any avowal of post-aspirationalism would be insincere. I’ve proudly banked the small societal and cultural positives I might have contributed to. But I’m angry, sad and riven by failure that, try as I have to the contrary, I will depart a world that’s in worse shape for my children (who never hesitate to tell me as much!) and grandkids.

I know this might sound old and grumpy. But moments of silence, inner and external, and the pursuit of tranquility, have become very important. I need classical music to drift softly through the house. So, too, do my dogs, who sit at my feet all day while I work.

The noise of the world distracts and grates with me more than ever. Far more than a lost tooth or aching hips. Even though later life self-maintenance means I’m probably in better shape than at 45. My youth has all but faded. I’m aware of that. But still, there’s something to celebrate about looking in the mirror at close to 60 and seeing elements of your long-gone parents’ faces looking back at you. And there is this: I have loved ones, deeply missed, who didn’t make it nearly this far. I am fortunate. They were not.

Meanwhile, acquaintances intent on curating perfect personal, social, creative lives on social media, I’ve had to turn away from, along with all social – and sections of old – media that cynically magnify and inflame the worst Australian traits of racism, division, welfare envy and cultivation of otherness.

Self-evaluation and self-understanding, which I ran from like it was wildfire until my 50s, has been and continues to be a fascinating revelation.

Money matters less. Not because I’ve got more but because there’s less I want to buy (dental work and physiotherapy excepted). I’ve long given away the fancy suits, flash ties and Italian shoes. These days I buy multiples of the same prosaic clothing items when I shop, much as I did 40 years ago. It feels more authentically me.

I’ve seen a lot of the world. Beautiful and terrible. But I have an acute three-quarter time wanderlust for places old and new. Tick, tick, tick. This, more than anything – except a deep hope that me and my partner together see our grandkids as adults and all our kids in their middle age – feels like an urgent reminder of the finite nature of it all.

I find peace and joy in small things. In talking until talk is exhausted – to strangers of all ages I encounter on walks, in shops, in taxis and at bus stops. In giving books I love to the people I care for. In the lives of neighbourhood dogs. In harbour mists and waking with every dawn. In the sight of Melbourne or Sydney and the continental centre – the interior and all the landlocked spirit it connotes – from the air. In watching my team win the grand final. In hearing about small, life-affirming acts of kindness – like my daughter giving her lunch money to the beggar at the train station. In books, of course. Forever reading several and writing one. Factoring in how much life of mine remains in books not yet written. A mate who is pushing 80 (now writing his “last’’, a memoir) urged me to get a wriggle on, not to ever again spend six years writing one, for I might otherwise have another 10 or 11 in me.

I increasingly dwell on my friendships. On what it means to be a “good mate’’ and on the fickle nature of so much acquaintanceship. In the past decade and a half or so I’ve cultivated more close, intense friendships based on genuine care and concern than I did until I was 40. But I suffer dickheads way less (there’s just not enough time for them, or for bad novels, shit movies, crap wine or rip-off meals) and I’m intolerant of social cruelty or nastiness, the holding pattern (along with alcohol) of so much superficial (especially male) bonding.

I celebrate all this, along with my friends and family, while thanking fortune I’ve lived long enough to comprehend their kindness, support and understanding when life has unexpectedly cut up rough. Which it must for all of us lucky enough to get (really or nearly) old.

So give me the prosthetic tooth. I can always get another if it doesn’t see me out.

• Paul Daley is a Guardian Australia columnist