Peg, try not getting started as you usually would. Try this: get a huge sheet of paper, tape it on a wall, and some fat magic markers, and write the main ideas in big letters, put balloons around them, connect them, brainstorm the project. Draw pictures of witches. What a new witch would look like. Try and generate some kindergarten fun around it. That might warm you up. At least it will give you some laughs -- don't get locked into the "writer sitting at her desk" mental model. Play with the subject for an hour.

yours, Peter T.