I like to think of creativity as the thrilling feeling of coming up with a solution to a problem where there is no guarantee that one exists. Finding your way up a rock wall, thinking of just the right word, and cooking, of course, all qualify as creative endeavors. I started thinking about it this way after reading a New Yorker profile of a famous chess player, and wrote about it here: http://differentkindofhuman.blogspot.com/2011/03/chess-infinity.html
To me, creativity is a process to deal with constraints. I'm less impressed by a chef using a chemical or additive, or using liquid nitrogen, than I am by someone who can find a way to make fresh local inexpensive ingredients appealing to both kids and adults.
I'm the most creative when I'm with other creative people. A good friend of mine from college and I used to talk all the time about books we had read or movies we had seen, or ideas that we couldn't work through on our own. I always felt like I was smarter with her than with just myself, because she was the perfect combination of challenge and acceptance, and through our conversations, I figured stuff out that I don't think I could have on my own. Also: The Voracity is amazing.
please remember two more important elements that could spawn creativity. reality and simplicity, each can lead to creativity.