I rode a fair amount between ages 35-50. Had no idea what cycling was about. But, I read a lot and learned to ride rollers so I was at least competent and not dangerous on group rides. Then from 50 to 59 I was off the bike. Actually didn't do anything. So, when I got back on the bike I was 25 lbs overweight. Having now been back on the bike for about 15 years I would emphasize a couple things. Ride as much and as consistently as you can. Don't worry about stats. You can do long slow distance (LSD) or High Intensity Interval Training (HIIT) but just spend time on the bike. And, this is the hard one for me, be patient. Don't have the expectation that a distance you do now at 10 mph will improve to 16 mph by next month. Focus on spinning, climbing, shifting, bike handling, etc. At the end of your ride if you are looking forward to the next ride you are doing it right. Good luck.