I'm 32 and my legs just reply "sod off" if I try and get anything extra out of them these days to the extend I've bought a turbo trainer to teach them a lesson!
I'm really happy to read of your return to cycling, mine came about after watching Trott and Kenny wipe the bankings with everyone in Rio
I was just the right age to get caught up in the mountain bike craze that hit in the early 90's and rode lots, mum used to find the summer holidays relaxing, up until the point at which we didn't turn up on time for lunch or tea as we'd ridden too far / lost track of time.
Went to uni, bike became transport, fun transport. It took less than 10 mins to walk from uni back to halls, I could take 40 mins on the bike having visited most corners of the city centre!
married someone with a car but kept cycling where possible as transport before being forced to move away and ended up with a train ride to work followed by needing motorised transport and that's been my decent into being rather more round than I used to be...
had good weather lately for yourself getting out on the bike?