Demian by Hermann Hesse. I wanted to scream "Stop overthinking!" to the protagonist. Something I can relate to.

Siddharta by Hermann Hesse. Helped me understand that a perfect life is a collection of ups and downs and that one must accept it all.

Amerika by Franz Kafka. Could relate to the protagonist because people take advantage of his naivety.

Factfulness by Hans Rosling. Made me see the world in a less pessimistic way.