"The Truth that Leads to Eternal Life" Note: not a positive change but a big one.
"Crisis of Conscience," "The Kingdom of the Cults" and "Jehovah of the Watchtower" both by Walter Martin, "The Four Major Cults" by Anthony Hoekema
(this batch undid the damage caused by my first listing)
"Principles of Accounting" Not an exciting read, but it started my career
"Alcoholics Anonymous"
My first college degree was in English with a history minor, the rest of my list would be too long to include much here. I need to mention The Complete Works of William Shakespeare, "1984" "Brave New World" "Lord of the Flies" and just about anything by Hemmingway and Faulkner, and if I get my sci-fi novel published, Robert Heinein, Larry Niven, and Jerry Pournelle.