It’s Saturday, and a longtime friend you never see is in town for just this one weekend. She wants you to go to the movies with her in the evening, but you have a report due Monday and you know it’ll take every available minute to finish on time. You’re in agony because you hate to tell her no.

Well, you’re not alone, according to psychologist Susan Newman, PhD, who authored The Book of NO: 250 Ways to Say It—And Mean It and Stop People-Pleasing Forever. Many people find it hard to utter that little two-letter word, N-O, especially women. This is because women are raised to be “nurturing and caring,” Newman says, and saying Y-E-S is a habit they’ve learned to please others.

But fear is also one of the reasons many women agree to all sorts of favors and tasks. Often, women fear they’ll be left out of a group if they turn down someone’s request, or they believe their friends may think they’re “lazy and uncaring,” Newman says.

But think of it this way, she suggests: When you say no to people, it’s a way of saying yes to keeping your life uncomplicated and easing pressure on yourself.