Just Say "NO"

It is not always a bad thing to tell people "no" in fact sometimes it is necessary. There are only so many hours in the day and we need to focus (read I need to focus) on the things that get me to reach my goals. I always have the best intentions on helping everyone and doing everything (mainly because I do things the right way and most other people don't). It seems that lately I have been saying "yes" to way to many things that later I have to go back and say "no" to. Why make it more time consuming than it has to? Why don't I just say "no" in the beginning? I am learning and being more realistic with my time constraints, but I feel this will be a battle that is not over yet.