And it isn't - as anyone who's put petrol in their car recently will testify. But there's a version of this I don't understand. I'm going to be forty next year and when I bemoan this dreadful reality, people often try and make me feel better by saying things like, "Ach away - forty's nothing nowadays" in the same way they talk about money.
It's not that I don't appreciate the thought - it's just that it doesn't really help, what with it being complete bollocks and all. Age isn't like currency. Years haven't declined in value. The last time I looked, they were each still 365 days long, which in turn are still 24 hours long and soon I'll have notched up forty of them - and this is Not Good.
And before you say, "You're as young as you feel" - that doesn't work either.
Because you're not...