How do you summon the muse?

I used to work as an artist full-time, and I've learned a few tricks over the years to help me create consistently, even when I don't feel very creative.
I recently read a book called "The War of Art" by Steven Pressfield that hit on a lot of what I've discovered and presented a lot more insight on the subject of creating and overcoming blocks.

So I'd love to hear what helps all of you out there stay creative and spark the muse. Are you willing to share your process and approach?