I got that from a friend of mine. She is a "glass half empty" kinda gal, but she's well aware that her attitude is less than positive and can poke fun at herself enough to crack a joke about it every now and again. We were talking about political correctness one night when she made some comment and I responded that she was one of the most cynical people I knew. Drawing on the PC nature of our discussion material, that's when she piped up and said "I'm not cynical. I'm realistically pessimistic!"
That being said, I printed off your saying and will take it to her. She will get a big kick out of it.
Brad