When do you believe?

Ok so my recent dilemma is when do you believe what someone says, when they themselves don't follow through with it? I will 100% admit that i am sure that i am at fault of this as well, but if someone says something don't you want to have enough faith in human kind to believe them? i don't care if what they are saying is good or bad, or a promise that they will be somewhere or do something. If you say something.... FOLLOW THROUGH! I used to be so reliable. If i committed to do something, not only would i be there but i would be 5 minutes early!! I get that things come up and stuff happens, but that is different then just being a flake or holding out just in case "something better" comes along. But if you tell someone never to talk to you again.... why would you call them?? If before you'd never agree to do anything with them but as soon as it is over between you that's when you want to see them, why would you ask them to come over?? It's like words mean nothing...

I still try to be true to my word, but the one thing i can't seem to stick to is saying NO. I have a disease to please. My heart literally aches if i have to say No. i would rearrange my schedule if i could to help anyone out. i don't know why, it is such a driving force. It is kind of a poison in the same sense. Sometimes i need to remember to think of myself too and what i need. it's not always about everyone else.

Anyway my goal is to A: be true to my word, and if i say something i am sticking to it!! and B: Remember that it is ok to say No some of the time.. and it is ok to take care of myself and remember what i need or want too!