Your only true possession is your human experience. It is the only thing that cannot be taken from you. Everything outside of you exists merely because you experience it. This experience is uniquely your own. It will never be entirely accessible to another, nor theirs to you.
Understanding this simplifies matters. For to optimize well-being, all you must do is design a life that allows you to experience more of it. Easily stated, but hard-won.
The next inquiry necessarily becomes, then, how to define experience. Experience is fluid, refreshing itself as each moment arises. It is fully formed by your feelings and stories. This combination of feelings and narrative characterizes your life.
Fortunately, your stories can be edited and your feelings can be challenged, allowing you to shape your future experiences. Being aware of this is a critical step on the path to well-being.