i have no idea what i’m talking about:
just riding around for a few hours is good, but will only really just make you hungry. The bicycle is a very efficient form of transport, by it’s very nature it allows you to be lazy and unfit.
what you want is to work so hard it leaves you feeling like you fell down a flight of stairs for a day or so…
find a hill, one that takes about 5 or 10mins to ride up.
ride up it, time yourself.
ride to the bottom, ride up again, time yourself
repeat once more, and go home.
(15mins high intensity is better than 3 hours pootling along)
if you feel ok the next day, you didn’t go fast enough.
don’t forget easy days, and a bit of stretching.