Yes. It is a vital skill to have in life. But you can practice it, if you work on it it will come in time believe me. You have to get straight with yourself and ask yourself who you are, what do you stand for and what are your principles. Principles are like guidelines, an inner compass if you will. You stick to it, no matter what. It's what makes you - you. If you follow your own rules and laws, a choice won't be a choice in any situation. The inability to say no usually comes from fear of other people's opinions. That they will think you are an asshole or ungrateful pos. This is already a learned behaviour in the past via abuse. Low self esteem might also be at play. Don't be afraid to lose people that expect you to serve them and they don't serve you in any way. Fuck this dynamic. I can't stress enough the importance of this. Sometimes, it is worth asking yourself - if you would ask that person the same thing, would they do it for you? If you want to find a real brother, someone with soul, make sure that what you are asking from your bro you would be ready to do for him at any moment. No questions asked. That's called love, respect and brotherhood. Those connections usually last eons.

Anyway, many people face this fear in their life. I did. You are not alone in this. Dig in, face your weaknesses, find out why you feel the way you feel and work on it. You've got this king!