#1 - I'm a lot slower than I was in the '70s + early 90s (as I ride more maybe some of the speed will come back)
#2 - I'm a lot more aware of vehicle traffic that I was (I suppose most of us are pretty oblivious / immortal when we're in our 20s)
#3 - I'm more ambitious than I was then - for a couple of years in the 70s I commuted to work on my bike (before I got a job that required wearing a suit) and would occasionally take a ride up into the Gatineau hills, but never anything more than 30 to 50km, now I'm commuting again and am taking reasonably long rides on weekends (Ottawa has some great bike paths) and plan on taking part in at least a couple of organized long rides (100km +) per year.