I'll go against the question since I believe this is about elevating one's thinking and not merely about books.
Just like learning the math theorem is practically worthless without doing the exercises (at least to me), I'll advise to just do something in the domain you want to be elevated in. Of course this doesn't apply to things you can't hope to do: for example History's lessons; Invading another country all alone is quite resource-consuming.
Having your outputs to show the outside world is quite gratifying! You're not a pure function.
Self Help:
* Craft your own time management system (and write and sell a book about it)
* Create a blog in which you ponder about life
* Try to gracefully start a conversation with random people. You never know what you can learn
* Begin a new sport, like climbing
Tech:
* Write a silly website in Typescript + React, or WebGL
* Craft a new small language of your own
* Do an HTML parser in APL
* Port a concurrent library to Zig
* Like pg says, identify things you think are the future and do things with them
Misc:
* Try to decipher a latin text just from how the words resemble the words you know
Basically just give some ressource to that weird side project idea that keeps popping up in your head.
Do the mistakes first, and only then learn the theory of what can work. And iterate back and forth between exercises and theory. Let the exercises guide what you want to learn. It'll help you deal with failures and lack of results and might even give you the freedom of being weird.