Many differing sources, starting with my old Jewish youth club leader (my adoptive mum, I adopted her!), (years of teaching how to get what you wanted) moving on the Jazz drummer whose 60's clothes boutique I worked in, (don't speak until they ask you for something) my parents "Just don't end up in jail son" (mum) "if you find a good copper (policeman) kill 'im before he turns bad", (my dad) and adding a plethora of East End characters who taught me to sell "If they ain't greedy son, you can't sell 'em nuthing" and (a classic) "If God hadden't made em to be sheared, He wouldn't 'av made em sheep" (both from a guy called Larry Lazenby Todd).
Books wise I started at the Bhagavata Purana, and moved through every religious book I could find except the Bible,out of curiosity, and owe a lot to Geoffrey Household for 'Rough Shoot' and Bob Heinlein for every book he wrote and I read, but eventually the book that MOST changed my life at 42 years old was the Bible, when I finally dropped my aversion to opening it.
All things we imbibe will assist, or inhibit our personal growth and development, physically and spiritually.
Experiences can open or close our minds and cause us to soar like eagles or skulk around like snakes.
Choices.... garbage in, garbage out.