last couple of years I've just seemed to 'quit' cycling for no apparent reason after building up a decent level of fitness, speed and considerable weight loss....
Much good sense written in this thread so far. In truth, this sort of deflation of enthusiasm happens a LOT and it happens to a LOT of people.
When I've needed to re-kindle my enthusiasm, I've started a little log (route, time, weather, what I liked, what I didn't etc). Not for publishing, just for me.
Looking back, I find old ones where I was clearly trying to get my weight down (bottom left of every page is weight in kilos).
I can see when usable computers arrived and I suddenly seem to obsess about average speed and all that malarkey...
But I digress. Keep a log. Keep it personal, just note what it amuses you to note and find the fun again.
It is fun and if you enjoyed it before you will enjoy it again. You posted here, so you clearly have an itch you need to scratch.
I am sure you will find the bug again and I wish you well.