Rewriting someone else

In 1Q84, a writer is rewriting the novel of a dyslexic teen who dictated the entire thing to a friend. He finds passion in rewriting it, because the story is very appealing to him and he wants to improve the writing to bring out the nugget of goodness within it.

I wonder if I could ever find energy to rewrite someone else’s work. I’m not so sure I could. If the story is already written, and already exists, in whatever form, I find I have less energy to create or change it. I have no desire to write fan fiction, for example, or ‘extended universe’ stories. I have far less energy to work on a story of mine after I’ve reached the end. I don’t know that I could ever find the energy to write about the same characters more than once, even.

I wonder about authors with ten or twenty novels in the same world with the same characters. I wonder how they stand it. Probably the paycheck helps.