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I'm collecting stories about how successful writers get their ideas. Here's another good one for non-fiction writers, particularly columnists, from Fran Lebowitz:
"When I was writing two columns a month, sometimes it was difficult to come up with ideas. I had certain friends that I have a humorous rapport with, and I'd talk to them on the phone until something came up. I made no bones about it. 'Hello, I have to write a column,' I'd say, and start talking. It was a way to hear my own voice back. I often found it useful in a pinch. Certain people inspired me or provoked something in me."