If you say that you will do something, do it. Otherwise, don't say that you will do something. This goes hand in hand with telling the Truth. By not keeping your word to others, you are basically lying to them. You may be coming from a good place when you say that you will do something, but if you are not 100% certain you can keep your word, then do not give it just to be nice. People make this mistake all the time. They agree with others and say things just to make them happy. This inevitably leads to disappointment since if you cannot keep your word, it is worse than not giving your word in the first place. Always keep the status quo between yourself and other people.