As usual, Wendy speaks for herself well enough I have almost nothing to add. :)
The Serenity Prayer is just one thing in a long list of things that I thought were cheesy in my youth and disregarded during my twenties, but which now seem great wisdom each year older I get. Who in their youth wants to believe they are going to counter the exact same kinds of problems that the last generation faced in their homes and ministries? It was easier to think that they talked so much about enduring because they had compromised at some point so that they were only just getting by in ministry. We, of course, would not make those same kinds of mistakes, because we, as new Bible college graduates, had greater insight into their mistakes than they ever had. To quote a college professor of mine, I speak as a fool.
Well, this much can be added, this was the naivete that all of us who helped establish a certain megachurch fell prey to, a kind of hubris and self-confidence married to a lack of thorough grounding in church history and theological tradition that led us to imagine that we were doing something really new instead of needlessly reinventing a couple of perfectly good wheels and butchering things up along the way.