Do you always feel like you have to say 'yes'? Well, you don't always have to. It's actually good to tell people 'no' sometimes. After all, you have things to do too and if you said 'yes' to every request then you would get nothing done. Also, people usually expect you to say 'yes' and therefore they get spoiled by this.
It's really nice to say 'no' when you really mean it. I've been doing this 'no' thing a lot lately and it's really nice. I mean, I don't have all the time in the world to talk on the phone to people. I have things to do. So, I tell the other person on the line that I need to go because I've got things to do. I hate wasting my time and talking too long on the phone is a waste of time to me.
So, tell your kids 'no'. You'll feel better and they will learn a lesson that they aren't always going to get a 'yes'. You're actually preparing them better for the real world when you tell them 'no' sometimes. After all, when they get out there and enter the working world, they won't always hear a 'yes'. Prepare them now. Say 'no' every so often.