As a writer, one thing we must learn to do, is move on from one project to another. Sometimes, it is liberating. Sometimes it is excruciating. Spending that much time on one set of characters, in one world, can be difficult to let go of.
We have to do this in every day life too. We must let go of places, hobbies, jobs, even occasionally people. Have you found ways to make it easier? How do you transition from one situation/project to another? Do you find change painful or exciting?