Finding a Form, Choosing a Genre, Embracing Your Nymph

A common question I get, since I wrote poetry and creative nonfiction, has to do with how I know what genre a piece of writing should be in. One answer I have given to this question is to say that the work will teach you its form, to just write, and see what shape it takes on. But there are other ways to think about genre, form, and what that thing you are writing wants to be.