Revision is like...

As many of you know, I'm writing a book about revision for teachers for Stenhouse Publishers.  It's going to talk about the process, strategies that authors use, and ways to use those same kinds of strategies in the classroom.  And I thought it would be fun to include some quotes about revision from writers of all kinds, young and old, published and unpublished.  So if you write and are okay with maybe being quoted, I'd love it if you'd fill in the blanks in this sentence:

Revision is like ___...