Enhancing Creativity

What sources have you found to be effective in enhancing your creativity?

During my adult years, I'd estimate about 25% of my non-fiction reading has been related to creativity, creative people and their process. Given the distance between cause and effect in this domain, it's unrealistic to expect I'd have seen any direct or immediate link from this reading to an enhancement of my own creativity. Still, my attitude remains - How can it hurt? Consequently, books or essays like this continue to have immense appeal for me. What have you read on the subject of creativity that you felt had a clear, if not immediate impact on your own?

How about people you've known? What useful guidance have you received from them? On first consideration, permission strikes me as a more apt word than guidance to describe how others have enhanced my creativity. And unlike with my reading, here the links are unmistakable. I can draw a straight line from some of my proudest creative moments to people in my life who have honored and supported my efforts.

Other effective sources? To this point, my experience with formal educational pursuits aimed at enhancing creativity has been a mixed bag and because it's a lot more expensive than reading, I've been more reticent. But if you have ideas, please share them with me or anyone else reading.