In more mature years it takes a bit longer for your body to build muscle fibre. Injuries take longer to heal, so you need to be more careful when working out. You can't train as hard for as long. Testosterone levels drop off (if you don't exercise).

Ageing just slows everything down a bit. But the processes still work fine. Apart from that there's not a massive difference for men. We don't have a menopause where our whole physiology changes like with most women.

The main problem with the average guy is they start doing less as they hit 40, e.g. because they give up playing competitive sports or whatever. Instead what they need to do is find something esle that has the same effect, to help retard the ageing process.

I would say all things considered, given the mileage I'm on, I'm probably in as good shape now as I've ever been. It's just harder work to keep it there.