You can't force creativity.
*Me takes devil's advocate position*
Not sure I agree. Keeping going when a task is boring and not fun is as much a part of it as the fun and inspired stuff.

For instance, I remember Frank Herbert talking about writing Dune, and how he'd sit down and do a chapter even when he was totally uninspired and it was the last thing in the world he wanted to do, and then he'd look back and be unable to tell the difference between the bits done when he was feeling inspired and creative, and not.

Then there's this quote (from another Frank coincidentally):

We should be taught not to wait for inspiration to start a thing.
Action always generates inspiration.
Inspiration seldom generates action.

Frank Tibolt