I've written before about the told-you-so brigade.
Today I had occasion to put my own advice into practice. My daughter used to dislike ketchup, but has recently started liking it so much that she absolutely floods her chips with it. She's all of eight year old so this is perfectly normal behavior.
Still, as she was taking a little good natured ribbing on this - I was able to pitch-in the words:"Its OK to change your mind".
I don't know how much she absorbed it, but I myself found it quite liberating to say so. So many times we tend to hang on to trivial stuff because we've always said so and because we are embarrassed about admitting that we were wrong in the past - but really, in so many cases, its OK to change our minds.