Don't have it. Searched for it quite a bit, looked through just about everything I can find on the internet until everyone starts repeating themselves, and the only conclusion I can come to is that there's really no secret other than putting a lot of effort into it.
This is a bit of a cheat, really, since I'm trying to come up with something to write every day (one of the "secrets" I've read about quite a bit can be summed up as "quantity, then quality"), and happen to be going through a bit of a creative slump. The problem isn't really that I have nothing to write about, it's the fact that I don't know what to say about the things that I've come up with to write about. Ideas are really, really cheap, I come up with them all the time, but good ideas are difficult. Even more difficult is doing something with that idea, so I have a bunch of half-written articles that I may never finish sitting there, just waiting for me to finish writing them. Once you combine the ones sitting here on the blog with the ones in my Dropbox with the ones in Google Drive, I end up with months worth of material if only I could finish them and know what to do with them.
Maybe the secret is that we're not even looking at how to be creative - maybe we need to learn how to execute instead of come up with creative ideas. We're actually really creative by nature, we're just not used to doing something with all of that creativity. Or I don't even know and don't have the authority to say anything and have anyone pay attention to what I say. All I can do is see the world from my perspective and say what I see.