Don’t be afraid to say, “No, thank you.”  Whether someone is asking you to chair a committee, or have another piece of pie, or have a drink, feel free to turn them down if that’s what you want or need to do at the time. You don’t owe anyone an explanation, though you can certainly give one if you want to. But remember this: some people will look at an explanation as an invitation to overcome that explanation. Sometimes it is safer to just say, “No, thank you.”