http://writingpad.com/interview-with-tv-writer-karen-hall/

8) You’ve been in the game writing longer than the average screenwriter. What’s your secret? I actually know the answer to this! Again, I have my mentor, Louis Catron, to thank. He started his classes by teaching students the importance of writing from a credo. He harped on this and made us actually write our credos. This gave me an early sense of the importance of “self as source” that I think it responsible for the longevity of my career. It is impossible to guess trends and figure out what “they” are going to be buying this year. But if I ask myself what I’m going through, what my friends are going through and what people really care about at present, I can come up with ideas that I’m excited about writing (so I don’t get burned out) and touch something in people because they are universal.