When I was running for cardio, it helped my motivation to have a friend to run with. We encouraged each other on days when one of us wanted to stay on the couch. Maybe there is someone whom you can find as a riding partner and motivate each other.
I'm 76 now and appreciate the low impact of bike riding. Thankfully I quit running before my knees gave out. I have a couple of friends I ride with but am also appreciative of the days when I go solo.
I have no problem with motivation as riding has become addictive.