Millennials, of course, rejected the cookie-cutter model of “being a grown-up” long ago. We have no blueprint for this stage of life that we’re happy with, so, with our well-practised anxiety amplified by a pandemic that won’t quit, the advent of our fifth decade is decidedly unwelcome. Turning 40 has, traditionally and paradoxically, been the age at which you’re supposed to have it sussed while also being the jumping-off point for a midlife crisis. It’s a nether world between youth and maturity that makes you feel like an awkward teenager again – an In-betweener, suspended between two states of being. I don’t feel like an old man, but I know, with triple-distilled clarity, that I’m not a young man, either.

Physically, the signs of age are there. My features are either a little drawn or a bit podgy. I’m ignoring phantom pains in my knees, neck and chest. My hairline, meanwhile, is tiptoeing backwards like a cartoon villain from a crime scene. And, according to science, from this point onwards, I can expect my testosterone levels to fall, along with muscle mass and sex drive.

Naturally, the world has capitalised on the insecurity that this drives. During my adulthood, the male grooming market has mushroomed into an $80bn industry. Viagra now costs the same as a beer and it’s just as easy to get your hands on. Targeted ads on social media bombard me with baldness cures, fitness plans, skincare and erectile dysfunction treatment. Meanwhile, cosmetic surgery and so-called tweakments for men are also growing in popularity. It’s true that we’re getting on, but we’re also doing more than any generation that came before us to hide it.

It’s a little sad that at this grand old age, so many of us should feel uncomfortable in our skin, but I get it. In my past three jobs, I’ve been the oldest person in the office. At least two of my bosses were younger than me. At the watercooler (or even on Zoom), you hope to exude wisdom and experience, while still being cool enough to get the modern cultural references. You send gifs in the group chat, nervous that it’s the modern equivalent of your parents sending a text message IN CAPITAL LETTERS WITH NO PUNCTUATION LOVE YOU LOADS WEAR A COAT.

I want to dress my age, whatever that means, without having to overhaul my wardrobe just because there’s an extra candle on the cake. I find myself uncomfortable (in more ways than one) in slim-fit trousers and a complete pretender in any kind of sportswear.

In truth, I have a better idea of how I don’t want to dress than of how I do. I don’t want to be another dad in a lightweight puffer at the school gates. Nor do I want to be a Mamil (middle-aged man in Lycra), spending all my money on Rapha and bike parts. And I flat-out refuse to be one of those fortysomething creatives wearing neckerchiefs with their unstructured tailoring as though they’d always dressed like Mr Wes Anderson.

So, how to play it? I could happily dip myself in vintage-inspired workwear, but even that comes with its issues. I enrolled on a woodworking class recently (because of course I did), then bottled out of wearing one of the numerous chore jackets hanging in the closet because – laughing-crying emoji – it felt inauthentic.

I’ve managed to find some hope, however. The meta trends in menswear today – more comfort, more practicality, less waste – are all things I support. I’ll happily slip into a pair of orthopaedic trail shoes because, sure, they’re trendy, but also the physio said something about hip misalignment. The same goes for nice trousers with elasticated waistbands and hoodies in the workplace. Mr Paul Newman was still wearing sweatshirts in his eighties. I don’t see why I can’t in my forties.

And here is where I find myself optimistic about the (admittedly dwindling) years ahead. The old rules about middle age – what we wear, how we relax, where we work – don’t really apply any more. I’m glad that there’s no longer a 40-year-old template to sleepwalk into.

It’s nonsense that life begins at 40, but research shows that it can be a decade of opportunity. Various cognitive skills peak during your forties, including the ability to learn and understand new information, plus recognition of other people’s emotions. My arithmetic skills will improve, which is handy because according to one study, I’ll also command my highest wage over the next 10 years.

Some tout the idea of “middle youth”, to describe the second wind that many feel at this age. I’m not sure that’s necessary (and it smacks a bit of denial). Wouldn’t it be better to exorcise the old stereotypes of middle age and just enjoy it for what it is: a new stage of life where you can set new goals and enjoy new freedoms?

Millennials already have a pretty good track record for redefining masculinity. My generation has played its part in questioning the status quo when it comes to identity, working patterns, mental health and fatherhood. Maybe we can do the same for being 40 and usher in a golden age for middle age. One of four-day work weeks, cashmere tracksuits and dad dancing in the metaverse.

I’m up for it if you are. Now, who wants to buy the old timer a birthday drink?