My thoughts ---
......Forget about legs hurting or not hurting,
Forget about 10 miles being good or 100+ miles being good,
......Forget about if you feel great or feel crappy after the ride is completed
Forget about whether a smile appears or a frown instead
Having gotten out for a ride and having fun should be enough to make it a GOOD RIDE!
For myself, when I have remained vertical while riding from first mounting the bike up until I dismount I consider a GOOD RIDE. Becoming horizontal via a Tom-Bay or a crash while moving has a propensity to put a kibosh on having been a "good ride." This means even bicycling 1.5 miles to local Walmart to food shop can be a good ride.
With regards to miles bicycled after "kitting-up" and getting the bike and all other things ready to ride, I strive for a metric century or longer. SW FL has no hills to stress my old muscles so once the pedaling begins with minimal coasting the miles just seem to pass by. Wednesday, my 69th birthday, was the only day I could ride this week so I started at 12:11AM, promptly got rained on big time but continued past that Mother Nature Birthday Present and finally finished 12.5 hours later with a GOOD RIDE of 141 miles. Next week maybe 2 rides of 100+ miles.