I always rode bicycles because it was fun. As a kid, I didn't have a very good bike, nor did I ride far or fast, but riding shortish distances slowly was still fun. Once I started earning for my living, I could afford a better bicycle (main difference being gearing suited for more serious hills), and riding a bit longer, faster became even more fun, so I was doing more often as well. Then came a new bicycle, even more riding, rinse and repeat.
Fast forward a few iterations of the above, and I'm still riding because it's fun. I ride moderately fast and moderately far, and my yearly mileage is quite low. I don't track my progress and I don't have training goals; I never go out to train, I go for a ride. Of course I like pushing and I like seeing higher speeds and more mileage, but I don't have a problem if my abilities go down when I ride less; it comes back once I start riding more. For this reason, never need motivation to ride - I ride when I feel like riding and I can make some free time.
My reccomendation is, stop making a chore out of a fun activity, and ride for the sake of riding, at least for a while.