In my 20s, I easily went from bike commuting to touring. I might ride a bit farther and harder during trip preparations, but then I'd just ride at a comfy pace for 6 hours or more. The only surprise I got was finding out I had no sprint left near sunset. I had no itinerary - I wound up averaging 30 miles a day. Very nearly 1/3 of the days, I was in a place nice enough to stay over. 1/3 I just moved down the road to the next nice place, and 1/3 I was interested in making miles. Those days averaged 60, but peaked at 140 downhill.
In my 70s, conditioning comes much slower.