I'm not quite a year into retirement. Luckily, I had practice being on my own because we all worked from home from March 2020. I have taken up pickleball, natch, and go to a weekly fiber artists meeting. Occasionally volunteer. I'm busy but at the stage where I feel like I need a bit more structure to my unstructured time, if that makes sense. If I'm doing art, I wonder if I should be writing instead, and vice versa. I'm retraining myself that it's okay to take a nap or "just" read a book.
Other than that, I haven't really missed my job. What I miss is no one asking me how to solve a problem or offer some strategic product thinking.