T. H. White
When Terence Hanbury White was 20 years old, he wrote his first book in Cambridge University. After he finish his study in Cambridge University, He got work as a teacher. He also continued writing, writting books about world outside of the building like hunting (killing some animals for food) and fishing. Few years later, his book about himself  England Have My Bones became famous and he might have decided to become a full-time writer.