why we say yes when we want to say no?

Yes,the reason you given is actually right for the question. The communication net of us hasbecome more important in mordern city,and in fact it is also helpful for the improving of our business. If we make other feel better,the oppotunity they like me would be more easy happened.Although we don't like person that act different with his saying, the praise is easier to open other's heart. In the history,a smart person was often popular than the straight-saying one.Maybe there also have a few persons like the next one because it been more truth,but they were uncommon.After all we are usual almost.

I think you hit exactly on the reasons! We are so conditioned to 'making' others happy. Women are especially vulnerable to this. We need to teach our selves and our children to not give automatic responses to all request, to take time to think about if we can or even should do what is asked. I am not saying we should all be self centered, but I am saying that ALL of need some time to ourselves, to not be serving others every minute. We must learn especially to not give in to emotional blackmail.