In the end, Ted Kennedy was a politician, plain and simple. Yet he embodied how politics and public service can be successfully intertwined. You cant be a good public servant without being a good politician. Kennedy was both.
If you get asked to do something that would take place down the road (say you get asked to speak at a conference that's a year away) and you wouldn't want to do it if it were taking place next week, then don't do it. This advice has helped me evaluate the opportunities that I truly want to dedicate my time to and those that I don't.