Creativity is connection.
The writer connects with his thoughts and memories and uses those to create new ideas.
The editor connects with his ideas through words and helps the reader, in turn, connect to the true meaning of what he is saying in the most engaging way possible. This ensures his meaning isn't lost because of spelling errors, misuse of words, typos, misplaced modifiers or inconsistent tone.
This connection, between words and meanings and between human and human, lights me right up, readers.
Taking a sentence that betrays the writer's true intent and then tweaking and polishing until it gleams, literally gets me clapping my hands! When a client sends me an email letting me know that I helped him express what he was trying to say, or writes to me with an alternate suggestion and I can feel his mind abuzz with possibilities, this common ground and shared creative process gets me excited. It makes me joyful.
Sometimes it even keeps me afloat.