I may be retired. I quit to be a trailing spouse, that ended up lasting a decade, and now I may never be employed again.
I would agree that you need to retire *to* something. But that doesn't have to be a calendar with every square packed with appointments and meetings and events. It can be "reading and gardening". It can be volunteering or quilting or golfing. Wood working, working out, whittling. Or likely a handful of those, or similar things.
My parents play lots of tennis. Mom does beading, which has expanded into teaching beading classes. They entertain frequently. They travel. Dad is on the board of their very, very large HOA. And other things.
I write, and take online writing classes. I read. I've learned to cook. Because my spouse works full time, I also do the majority of the housework, which will decrease once he is no longer working in some number of years. And other things.
The question can be boiled down to "what do you do when you wake up Tuesday morning"? If you don't know, that's not necessarily bad. That could mean you haven't thought enough about it, or too many things appeal to you and you are struggling to narrow it down. Or, it could mean that there's really nothing that interests you, in which case you are likely to struggle.
So imagine you've been retired a couple months. You are all caught up on sleep and feel decompressed. You wake up. It's a Tuesday. What do you do, or what do you want to do? If you can come up with a rough answer for that--that a hard schedule, but just a list of things you think you might like to try, whether it's Tuesday or the following Friday or the next month.
Sure, but for a lot of us, it's impossible to know what we'll want to do on Tuesday morning, months after we stop working and are in a completely different headspace because we've finally decompressed. Obviously everyone needs activities in retirement, but for many, it's not at all necessary, or even feasible to be able to identify them in advance.
I had very, very clear ideas of what I would fill my downtime with, because I knew exactly what my hobbies and interests were and anticipated doing more of them. Well, that was totally wrong. It turns out a lot of my old hobbies were ways to manage my stress and tension, and now that I have so little stress and tension, I'm far more interested in things that I wasn't before.
For example, I expected to take on a ton of writing projects. Nope. It seems that writing is something I do to channel frustration, pain, and anger. Less frustration, less interest in writing. I haven't written a proper page of content since early summer, and I don't miss it. I've turned down a few projects.
Meanwhile, I read a fiction book for the first time in over 20 years. Until last week, fiction to me was a complete waste of time. I consume books like they're skittles, but only if I can learn something important from them. However, last week I shocked myself by choosing a fiction book, and I was actually able to vaguely enjoy it. Who knew?
I also haven't painted in over 2 decades, and just thought yesterday: "maybe I should paint something for that wall". Long story, but yeah, there's a reason I don't paint.
Months ago I baked a god damn pie. I DO NOT bake. Baking is not a thing I do. I cook, and I adore cooking, but baking? No. Then suddenly I smelled a neighbour baking something apple-y and said "I'm going to bake an apple pie!" and I did! Despite never particularly liking apple, of all pies.
Basically, my DH thinks I've been swapped out for a pod person because I'm slowly coming around to all of these things that I not only did not do, I LOATHED them. Seriously, had you told me a year ago that I would use my newfound free time to bake an apple pie, read fiction (and not even historical fiction), and am considering painting (of all awful things), I would have made a face and imitated vomiting. Honestly, I still might, it's all that anathema to me. I'm truly baffling myself.
My point being, for some of us, it's impossible to anticipate what our needs will be once the demands of work are alleviated, especially if they're intense. There can be such a huge difference between what we do in our downtime between work obligations, and what we do when we are totally free of obligations.
It's hard to tell what kind of people we might become under completely different circumstances. Evidently, I'm becoming someone who likes to do shit I used to hate. Go figure.