How did Rick Riordan become a writer?

Rick Riordan was a teacher. When his son was in second grade, he hated school. He was a very slow learner. He was diagnosed with ADD and dyslexia. To make him feel better, Rick Riordan made up a bedtime story about a Camp Half-Blood and demigod heroes. The son made him write it down, even though Rick Riordan thought he would never write it, let alone make it a book. He didn't expect it to sell either.