The old thing is from, I believe, one of the Marshas, and has has to do with writing something that the author would like to read. Everybody knows you can't predict the market: if sci-fi is hot, by the time I get my tentacled Nanking Molestas underground on Planet Baloney, that surge is over and Talking Critters are all the rage. Sure, it's natural to imitate successful things but the point is this: are you having a good time, or do you get up from your desk feeling exhausted and discouraged? I've asked students point blank (Really? You, Ron, Mr. Diplomacy?) why they don't write what they'd love to read and they tell me they'd be embarrassed or someone in their family would get her feelings hurt.
Try embracing Shame and Fear in 2010, inviting them in and see what they have to tell you. I've had their hot breath in my shell-like ear, and -- believe me -- it's a rush!