Meditations by Marcus Aurelius is a good entry point. These are reflections of someone who had "everything" for its time (emperor during the golden age of the Roman Empire). It is an eye opener regarding how having things and being rich and powerful doesn't solve anything with what is the meaning of a life.
It is about about differencing what is in your control (what you think and do) and what is not (outcomes and what others think of you), doing what is right with courage and not worrying about outcomes. Ultimately because caring about the opinion of strangers who like you will soon die and be forgotten is pointless. Nobody cares if you're successful in your life, close friends and parents, while they are still there, only care about your happiness (and if not you can then confidently ignore them).
Also the book Sapiens was another eye opener for me on what is physically real and what lives in our mind collectively (nations, institutions, companies, money, relations, the name of things, ... or simply all the things other animals don't see are in our mind). Seems obvious but really working on intuitively knowing to differentiate the two really helps with identifying what problems are real and what problems are juste consequences of mental constructs, and so are self-imposed.
Don't want to spook you with spiritual bullshit but also mindfulness meditation (stoping thoughts, focusing on breathing and experiencing all senses) really works for me for experiencing all of that and happiness without any material thing or doing anything. I could be billionaire nothing I could buy could significantly really improve my life in a meaningful way. Nature will not be prettier, I will not have better friends to laugh, my coffee will not taste significantly better, ... Material thing and experiences are nice of course, I would absolutely enjoy them, but like all things they will pass and leave only insatisfaction if I crave or cling on them too much.
Would you mind talking more concretely about this?