By “changed your life,” this can mean your outlook on life, belief system, how you communicate with others, or simply the way you think.
For me:
Non-fiction: The Body Keeps the Score by Bessel van der Kolk — Helped me understand myself better so I could regulate my emotions. Also influenced how I think about and empathize with others.
Fiction: Bewilderment by Richard Powers — Changed how I interact with the environment more than any work of non-fiction. A masterpiece that will leave you a sobbing yet more thoughtful human.
by horrorbooksandaliens