I had a pain in my tail bone the other day. It's a peculiar place to feel sore, so I asked my mother to have a feel around to see if she noticed anything untoward.
She didn't need to. "I had it too!" she said at once. "Excruciating pain - the worst ever. I couldn't even sit in the bath."
"But what is it?" I asked. "Oh, your bum has dropped," she said casually. "It happens when you get older. To be honest, health insurers should really provide for bum implants because it's very uncomfortable."
And then she went back to reading her book.
My mother has made sure to keep me up to speed on the less talked about aspects of the ageing process, even if I don't particularly want to hear about them.
Did you know your nose changes shape as you age? I didn't either.
Apparently your lower lip drops too, exposing more of your bottom teeth. I know, I know - it's hard to hear, but there is a silver lining, according to my mother.
"Your eyesight deteriorates as you get older so you can't see how awful you really look in the mirror."
When does middle-age begin? Opinions vary. Some say it starts at 50; some say it's as young as 35. I think it happens the day your mother tells you that your arse has dropped.
A dropped bottom consumes an awful lot of your mental and physical energy. I have essentially put a line through anything that resembles free time in my diary and replaced it with squats, lunges and donkey kicks.
I was going to start volunteering with a local charity but I'd prefer to raise awareness of dropped bottoms and the devastation they can cause.
The trouble with this all-consuming fixation on the physical signs of ageing is that we forget about the mental signs of ageing. It's easy not to notice that you just said "good girl" to the teenage waitress when you're busy discussing the best Botox doctors with your best friend.
When you believe that green juices are the fountain of youth, you tend not to notice that you've been extolling the virtues of the NutriBullet with the maniacal enthusiasm of a brand ambassador for the last hour.
Maybe this is why middle-aged men look like they have been pulled through an electric fence backwards. They can't fantasise about bum implants and youth serums. They look more world-weary than their female counterparts because they have faced up to the horror of middle-age and the dubious future of sensible shoes and reliable laxatives.
I went to dinner with a male friend recently and I nearly fell off my chair when he bemoaned the industry in which he works as "a young person's game". He's 32.
This statement was as symbolic as a single grey hair in a sweep of otherwise raven black locks.
I was going to tell him that my bum had dropped but it was clear he had his own issues.
The first signs of ageing aren't always physical. Our thoughts, beliefs and attitudes mature too - and not always for the better.
Often the very first signs of middle-age are antisocial tendencies, which are characterised by a delight, bordering on the euphoric, when you receive a text message that reads 'do you mind if I raincheck?'
I've already reached the point where 'going out out' three times a year seems perfectly reasonable.
Indeed, when I go out for dinner with my friends and someone wonders out loud where we'll go afterwards, my initial reaction is "Have you lost your mind?! It's past midnight."
As for rollovers... is that a dessert? Either way, I'll pass - I forgot my Rennies.
When people ask me how my weekend was, I wonder what exactly they're getting at. Surely they don't expect me to tell them that my Saturday was entirely based around buying padded hangers in Dundrum Town Centre?
Speaking of which, you know you're approaching middle-age when the very idea of Dundrum Town Centre, or indeed any large shopping centre, makes you break out in a cold sweat.
Early morning phone calls are equally anxiety-inducing.
Last month, my cousin called me at 8am.
When you're in your 20s, early morning phone calls generally involve a friend slurring down the phone before passing the receiver around to the entire party (and then completely forgetting that they called you).
When you're in your 30s, early morning phone calls are clearly a sign that someone has died.
"Is everything okay?" I asked my cousin as I tried to steady my breath and brace myself for what was about to come.
"Er, yeah, just ringing to wish you a happy birthday," he answered.
I was 32 - much too young for this kind of shit, but much too old to care.
'A dubious future of sensible shoes and reliable laxatives'