45 and mountain biking for 25 years in September and I’ve done my 3 longest off road rides in the last 3 months, 40, 44 and 84 miles so it must be doing something good. I haven’t got any faster or braver or more skilled in all those years but if I can still do 84 miles of the South Downs Way in 9 hours 59 minutes, get the train back to Brighton, ride a further 7 miles home, have a shower then go out for the night without falling asleep in my dinner then I reckon It’s keeping me pretty fit. I put it down to riding everyday to work off road for the last 3 years and extended the ride whenever it’s nice weather.