Harriet Walker: 'I understood with crashing clarity that I was old'

When was the last time you had a weekend you would categorise as perfect? The definition changes with the seasons, or the personalities we put on with each phase of our existence.

But it goes along the lines of: something fun – exciting, even, let's not sell ourselves short – followed by something undeniably lovely; a burger, say, or a cuddle with a tiny dog.

Until recently, my perfect weekend would have been: drunk with friends, drunk with boyfriend, some eating in between, topped off with a spot of laundry, a box set and the sort of drink that feels amenable to the invariable winding down that must take place of a Sunday evening. A bottle of red wine, say.

I say until recently because something very odd has happened in the past few months. The glass of wine that might once have been the gateway drug to several bottles and a night doing improvised karaoke on public transport now means a banging headache and a lingering sense of unease. I've tried everything – drinking less, drinking more (the logic being that, if it doesn't even touch the sides, the sides won't complain the next day) – and nothing works. Nothing dulls the solemn ache of guilt and fear that drinking on a weeknight brings.

And drinking on a weekend seems to have swiftly followed suit. Yesterday I organised, over email, a night out with my drunkest friends. Clearly the terror had hit them, too. "I've realised I can't function when I drink," one said. "Which is a bore when you're an active alcoholic." "I'm not drinking in the week either," replied the other. "Christ."

In the end we decided we had to drink. "The good thing is," my friend reasoned, "if we are drinking, we won't get as drunk as if we weren't." The logic here is both incomprehensible and infallible.

Anyway, last weekend was perfect in my newly revised book – that is, The Book of the Bore. It incorporates the sort of meandering indecision and pointlessly allegorical unveilings of morality that characterises much medieval poetry, ending with a similar showdown against a metaphorical dragon, either in valour or public humiliation.

The perfect storm of a weekend, I thought, had brewed: drunk with colleagues (Friday night); drinks with extended family (Saturday afternoon); sofa time (Saturday dusk); drinks with friends; drunk with friends (Saturday; Saturday); and then Sunday. The sort of Sunday where all you really do is watch The World at War and tell yourself that life could be much, much harder. Like, blackout hard.

But I realised steadily, as Sunday night drew in and I still felt sick from the night before – in the way that truth dawns upon someone who has been lied to for a long time – that the part of the weekend I had enjoyed the most was the minority window I had spent lying on the sofa with the heating on full-blast, reading the papers and various magazines. It was akin to the moment of realisation I had a few months back that an avocado can be so much more than merely a vehicle for vinaigrette. With this double realisation of how comfortable I was (both literally and metaphorically), I understood with crashing clarity that I was old. The following three days were spent researching Retinol online.

At first I was very worried. But then I felt grateful. Grateful that my transition from the days of dancing on tables to those of sitting comfortably with an orthopaedic cushion had not been too stark. Indeed, it had crept up on me without my even noticing. It was like gentle hair loss: reaching and finding there was less there than before, rather than going to fluff my quiff and discovering I was bald.

So I plan weekends now with a sense of foreboding, fighting the temptation to neck a bottle of Baileys on my own in front of Strictly just because, and with the knowledge that Sunday could be spent "doing a walk" on the Heath, or strolling round a gallery.

That fight really hit home on holiday earlier this month, when days were spent looking at historical European art and nights were washed away in beer. It's easier to marry the two in Berlin, where it's totally acceptable to get up at midday, eat sausages for every meal and not have a job.

So it's up to me to make this work at home. We'll see how it works with my drunk friends (prediction: messy) and with my more sensible friends. It depends, I think, on how comfortable I am being the only person drinking during daylight hours when no one else is. What it might end in, I think, is me fast asleep on the sofa before the bell has even tolled 7pm.