I sing both in my shower and in my car mostly in my car because I have this weird thing - whenever I'm singing to the radio - my friends kind of hate it - but I pick out the harmonies in my head and I'm singing the harmonies to the tracks and I'm jamming it out.
Beyond that I seem to be compelled to write science fiction rather than fantasy or mysteries or some other genre more likely to climb onto bestseller lists even though I enjoy reading a wide variety of literature both fiction and nonfiction.