1. We say no to all manner of things that we might previously have accepted This includes any social engagement that requires standing up for extended periods.
Gigs - once my night out of choice - must now be seated and within an hour's travel of my home. Queuing to get in anywhere is out of the question, and music in bars must be low enough to allow conversation.
Table service is preferable; clear access to the bar and clean loos are non-negotiable. A last-minute cancellation feels like a Lotto win for all concerned.
2. Aches and pains become A Thing Every time I move my neck or wrist after a period of inactivity, I hear the sound of someone gently palpating a bag of nachos. Noisier still is the grunt I expel as I hoist myself from a chair after dinner. I now need reading specs, which I clean by leaning over an open dishwasher door and waiting for them to cloud up.
3. We want fewer, but better friends I simply don't have the time to spend on crazies (a madness score of up to 7/10 is within normal range), untrustworthy gossips or joy-sappers. Friendship is suddenly every bit as important as it was at 4 years old, except you don't attempt to woo those who don't like you.
4. We don't entertain any holiday accommodation that's less nice than where we live I'm old enough to know and accept that Dubai is not for me, and am cheery in the knowledge that I will never go skiing. Otherwise, any week off in which I laugh, eat and watch films somewhere lovely with my partner constitutes the holiday of a lifetime.
5. We can deal with nuance Having spent my teens, 20s and 30s feeling certain of my every opinion, I'm now far more likely to say "I don't know" or "I don't think it's that simple". This extends to politics, relationships, jazz music, caravans, religion and Taylor Swift - but not karaoke or offal. I walk away from arguments not because I'm more tolerant, but because I can simply no longer be arsed. The more I know, the less sure I am of anything other than that life is messy and most people are well-meaning and essentially good.
6. We have irrational crushes Having been dismissive of their abject uncoolness in my teens, I now really, really fancy Take That.
7. We wonder about those in charge I look at almost everyone in a position of authority and invariably think they look about 9. I'm shocked that anyone other than my children was born post Berlin Wall and Bros.
8. Death becomes a preoccupation Not in some nihilistic or maudlin way: I think about death every day simply because I am more accepting of its inevitability. This is in some ways positive. I now collect happy memories obsessively, take time out to enjoy my loved ones and actively plan things I want to do, instead of putting them off. But I become furious at all the obnoxious people allowed to live while my loved ones are stolen by cancer.
9. We know the price AND value of everything Despite my new-found appreciation of the preciousness of time, I waste hours on irrelevant pursuits. I can digest a week's worth of junk mail catalogues in one sitting. I now keep warranty cards, register appliances, insure everything and never let my AA cover lapse, because I no longer enjoy the blind optimism of youth.
10. Looks still matter to us I am disbelieving of those who claim not to give a damn about their changing face and body in their 40s. I'm not thrilled that my eyelids are hooding, and I definitely care that I'm a dress size bigger. Just not enough to get surgery, do yoga or pretend that shredded courgettes are a substitute for spaghetti.
11. We can say sorry I am able to say I made a mistake. I make hundreds and I'm happy to say so because the belligerent are completely unbearable company.
12. Crying also is A Thing I cry often - at game-show wins, song lyrics, old couples holding hands, dogs with jobs, anything involving war veterans, David Attenborough documentaries (especially about polar bears) and, yes, even the John Lewis Christmas advert.
13. Fashion becomes complicated I have, for the first time in my life, stopped to consider the concept of "mutton dressed as lamb". I carry flats in my handbag, wash tights in a hosiery bag and refuse to buy anything that needs dry cleaning.
14. Just one glass too many can tip us over the edge I can no longer drink alcohol until it flows from my eye sockets. Today, my head spins and my hangovers are biblical. Two nights out in a row are out of the question. I find myself being the tedious party guest who alternates proper drinks with sips of Pellegrino, then leaves without saying goodbye, in time to catch the third-to-last train home.