I started riding as an adult in the early 80s when I was around 30. I did it to get in better shape for off-road motorcycling and I was also a smoker.
I started with 5 mile loops on a flat bike path near home. I was pretty proud the first time I did 2 laps the same day. I met a guy there who became a great friend and we eventually tried some hills and longer rides. I quit smoking and we joined a local road club and started doing centuries every Saturday.
I also love riding a mountain bike off-road, (gave up the motorcycles). There are different ways to enjoy bikes and you can do it for decades, just keep it fun. What has helped me keep at it is meeting other riders and becoming friends with them. It adds to the enjoyment to have friends to ride with.