I can think of three books that I think are a big part of who I am.
The Discworld books influenced my ethics and morals quite a bit, while being at the same time being funny and witty.
Kitchen Confidential by Anthony Bourdain was the book I read in college and instead of going to university I ended up working as a kitchen hand. I did eventually tire of the work hours and bad pay, but it was in a kitchen I learned what work ethic looks like.
And of course, The Hitchhikers guide to the Galaxy taught me to always know where my towels is.