I'm coming up on 1 year post retirement, but I had already been doing a lot of groundwork (developed an artistic practice, volunteered, took a writing course, etc). I live alone, never married, no kids. Yes there are some days that feel somewhat purposeless but I think that's a function of 45 years of being told "you must be productive."

Maybe instead of thinking about how you can "fill" your time, you think of it as how can you live your life free of the demands of bosses, meetings, and other people's schedules? I love the freedom of deciding that this morning, I played pickleball instead of the fiber group because rain was in the forecast for my usual Friday game. And I didn't have to answer to anyone to change my mind!