Why saying no is difficult????

In this world many a people just can't think of having to tell people they can't do something. Or they feel obligated when a colleague or a friend asks a favour. Sometimes it so happens that even if we want to say 'no' direct on face we simply fail to do so. I personally feel if a person is of low self-esteem very often has a lack of assertiveness and believes he has to meet the expections of others. Saying no is very difficult for them. But if we do things against our will this will result in a wired feeling of being used which inturn has an indirect negative affect in our personality. hence the best way to avaid this kind of situations is learn to say a NO. A simple and direct "No I am affraid that I will not be able to help you out now" can be the easiest way of making your stand firm without using any hursh tone or word. But yes, if requested for something then it can be responeded in a possitive way like " I would definitely try to do that but may be after sometime/ after i finish my assignment." I would like to cite another situation where a clear and bold utterance of NO is adviceable in order to avoid further problem. In case of working women there are hundreds of situations where a male boss very often tries to abuse them physically or mentally. In those cases women should take a firm step in opposing such craps and making the boss keep a safe distance. If someone tries to enter into your personal space then he/she should be stopped there only. I think and strongly feel that women those who are little hesitant of uttering NO should literally learn and practise saying 'NO'. Sometime expression, gesture and body language also give the same massage but still if we learn how to say NO it will definitely help us in keeping a healthy and long term relationship with our colleagues, neighbours and other accuintences.