Books that changed my life? There are so many!
Here is one: A Wild Sheep Chase By Haruki Murakami.
Before I went to university I read strictly for pleasure. The fiction of Heinlein, Asimov and Vonnegut made up the bulk of my reading. Then in University I was taught to appreciate "literature" and soon found myself not only reading but actually enjoying the works of Faulkner, Pynchon and Nabokov. Out of university my first job was working in a bookstore and here I read A Wild Sheep Chase - a book that perfectly mixed the pacing and plotting of my pre-university reading with the thematic concerns of all the heavy-weight novels I read in the ivory towers. Murakami open up whole new possibilities of what novel could be for me. It also made me want to turn on as many other people as I could to the fantastic Japanese writer, which in turn made me passionate about book selling. I remained a book seller for seventeen wonderful years thanks to books like this.