Assertiveness and limits

I like to think of myself as a nice and accomodating person. I want to be helpful and I want people to be happy. The problem is that I sometimes forget to think of myself because I'm so busy thinking of others. Everyone always tells me that I need to set limits and learn to say "no". I hate doing this because I like to do everything, I want people to like me, and I also sometimes feel more confident that things will be done right if I have my hand in them.

However, there are times when setting limits becomes absolutely necessary to make sure I do not allow myself to be used up and burned out. What I always find interesting is that people respond well when I set reasonable limits. I hate telling people not to do certain things because I'm afraid they'll be mad or feel put out. But what generally happens when I set limits so that I can stay sane, is that people respect them without too many problems. Other limits, such as whether or not a kid can have ice cream, are another issue altogether--they don't generally respect those types of limits. However, if I command a little respect and consideration of myself, I usually get it. This will never make sense to me, but if it helps keep me sane, it's a good thing.