Suggest me a book, that helps getting to know myself and making a thoughtful decision

Hello guys, I'm looking for book recommendations that could help me in a very practical way.

I am currently in a quota: I continue to study political science or I change my subject to psychology, law, economy or something else.
I already deal with the various topics, but it is difficult for me to make a decision that suits me.

Are there books that helped you with such road decisions?
Philosophical or practical advisors to choose the right way for yourselve?

I am open to any kind of literature, be it life guide, diary of a samurai or the works of a Greek philosopher. I want to deal with myself and my way productively and need guidance through clever thoughts.