My Dad you to say this as he was always being asked to help out a local club or committee.
The ability to say "no" in the work place is such a powerful place to be. The point being is that if you are continually asked to help out it is probably on the "no-win" type of tasks that other are having trouble with!
This is a concept that I've always battled with but I read this blog from the wonderful Shane Parrish, and have nothing to add. Definitely subscribe to the Farnam Street blog if this stuff is of interest. Here is the full article -
Understanding Speed and Velocity: Saying “NO” to the Non-Essential _ Farnam Street
