To learn to say no, we have to first understand what’s resisting us about it. Below are common reasons why people find it hard to say no:
You want to help. You don’t want to turn the person away and you want to help where possible, even if it may eat into your time.
Afraid of being rude. I was brought up under the notion that saying “No”, especially to people who are more senior, is rude.
Wanting to be agreeable. You don’t want to alienate yourself from the group because you’re not in agreement.
Fear of conflict. You are afraid the person might be angry if you reject him/her.
Fear of lost opportunities. Perhaps you are worried saying no means closing doors. didn’t want to say no as she felt it would affect her promotion opportunities in the future.
Not burning bridges. Some people take “no” as a sign of rejection. It might lead to bridges being burned and relationships severed.
From Celestine Chua of The Personal Excellence Blog.