Was discussing this very subject over a beer with an old schoolfriend last night.
We reckoned you’ve become middle aged when:
1. You make noises when rising from a seated position.
2. You give out an involuntary sigh of contentment when handed a hot beverage.
3. You are staggered by the fact that you meet professional people (doctors etc) who weren’t even born when you started college / your first job
4. You realise you’re starting to sound like your Dad.
You also get bonus points for membership of any of the following:
Ramblers, RSPB, National Trust, English Heritage, Camping & Caravanning Club
I tick most of the above boxes, but to balance that like Wrightyson at 41 I’m still skating and thrash my singlespeed like it’s a big BMX.