Well... this is a complicated subject for me. I don't think I can offer you much of anything in the way of useful advice. But I'll share my own experience with you. And, perhaps, there'll be something in it that will be instructive.

I actually ceased to be employed in my early 50's due to a combination of medical as well as mental health concerns. My wife supported us. (She had always earned more money than I did anyway.) I never really developed a plan for how I would spend my time. (I didn't have any real hobbies either.) But I just naturally assumed the role of a house husband since I had always tried to do my share anyway and I felt that if my wife was going to be supporting us it was my responsibility to keep the home fires burning, so to speak. I did pretty-much all the housework, most of the cooking, cared for the dogs we had during those years, and did home improvement & repair projects. So I kept busy. (Now I'm 72. So I am officially, so to speak, retired.)

On the other hand, as busy as I kept myself, there was still plenty of time for me to ruminate on all of the failures in my life as well as my (secret) unresolved transgender issues. And, as a result,

I did try doing some volunteer work during those years. But the difficulty I had always had getting along with people in a work environment coupled with my mental-health-related struggles, ended up tanking those efforts. And, after a while, I just no longer had any interest in trying again. So gradually I became increasingly reclusive to the point where, with the exception of still having my wife, I'm now thoroughly reclusive... an urban hermit, if you will.

Physically I don't think not being employed was ever a problem. In fact, I lost weight & was much more physically active than I was when I was employed. Of course now, at 72, I'm feeling the physical effects of aging. But I also think there has been a very gradual decline in my mental acuity over the years. It wasn't really noticeable for most of the past 20 years or so. But I've really begun to feel it's effects over the past year or so. I now struggle with a lot of generalized anxiety, fearfulness and (I suppose) depression although I still get up every day and do whatever needs to be done. I've also begun to experience some "symptoms", so to speak, that seem similar to what is referred to as "Sundown Syndrome". (Sundown Syndrome is often, but not always, related to senior dementia. So far, at least, I don't think I'm in the early stages of that.)

Would I have encountered all of the difficulties I encountered had I kept working? Of course there's no way to know. My inclination is to say I was probably headed downhill at that point in my life anyway and working, or not working, I was headed for trouble. It would probably have just been trouble of a different kind had I stayed employed. So that's what I can tell you about my experience of being retired (both unofficially as well as officially.) Hopefully somewhere within what I've written there's something that can be of value to you. Good luck!