Harriet Walker: There are good things about turning 28. "You'll stop being mental," said my boss

It was my birthday last weekend, which means a certain amount of time has passed since it was last my birthday.

I'm not going to whinge about my age, because that incurs the wrath, fury and exasperation of people older than me, and the pity of young bucks who have not yet reached the not-really-a-milestone of 28. (Just you wait, young bucks, just you bucking well wait.)

"Twenty-eight is the best year!" trilled several work colleagues. "It really is the best, because 27 was terrible for me, and then 29 feels like the end of the world. Twenty-eight was the tops!"

As I recall, 19 was pretty good. Nineteen is the age I think I am in my head, which has baffled me in the past when I've failed to enjoy going to terrible nightclubs, talking to men who bore me or been unable to button up my denim hotpants. And also every so often when teenagers on public transport fail to return my "We're all in together" shrugs, or to even clock my existence, and I realise I am, to them, at least, in their first flush of social tadpoling, a wizened old crone. Except I'm not even that. Because I'm not even in their field of vision, like the opposite of those notes that only dogs can hear, but visually.

Actually, 27 was pretty good, too; 26 was awful; and at 25 I was really fat. Don't worry, that isn't going to be how the rest of this column goes.

At 28, I have the following things to look forward to, apparently – and these are all mined from what my elders have said: 1) I will no longer be able to tolerate alcohol in measures larger than a thimbleful, because of hangovers that resemble Dantean hell. Which is just as well, because, 2) I'll no longer crave alcohol in the amounts (biblical) I did when I was 27 or 26. Especially 26.

3) I will no longer be able to eat anything that tastes nice without noticing an immediate increase in my girth or how much my bum sticks out as if it has a mind of its own – which it does, according to 4) a phenomenon whereby I will suddenly notice something resting on the back of my legs before realising it's my own arse. (I've already noticed this, actually. At first, I thought I was being molested by a third party on my way to the bus stop.)

But enough of this; there are good things, too, I'm told. "You'll stop being mental," said my boss. "You'll just [mimes flicking a switch] and dah-DAH! You're not mental any more."

This can't come quickly enough as far as I'm concerned. I've had it up to here with being governed by neuroses in the same way a puppetmaster controls his characters, except the strings connecting me to them are all made of deep-seated jangles.

"It's true," someone else offered across the desk. "Annoying people won't even annoy you any more." (It is nice having a relatively new job where people don't know you well enough and assume you're as easygoing as a normal person when it comes to what annoys you.)

For me, the weird thing about getting older is not that I worry about what I will become (essence of dust), but what I will no longer be: box-fresh with a guarantee if I become faulty, with all my factory settings intact.

But where's the fun in being a blank slate, even if you do have optimum functionality? It's like Keats said: life can be a bit rubbish sometimes, but you need to have really felt like detritus so that you can fully appreciate those rare times when you feel the absolute tops. That was him, right?

I'm trying not to mourn not being quite as hot-off-the-production-line and glitch-free, because I'd rather focus on what those glitches have made me into. Just as silver, when it is scratched or bashed, doesn't look any worse for the wear and tear, but rather shines from new angles, assuming a new aspect. (I'm not talking about wrinkles, obviously – I'm as terrified as the next vain person about those.)

The other thing I realised on my birthday is that I should stop putting things off until there is an ideal moment in which to do them. I realised this as I finished a third cocktail before 2pm, having made the least of the sunshine and by now feeling a bit sleepy. As I went home for a mid-afternoon nap (old, you see), I thought, "I mustn't let the beauty of every day pass me by, in anticipation of better things to come."

I didn't make it out to the cinema that night, either.