How hard is it to say "No"? Pretty difficult for some of us, especially in certain situations. Overly easy for others. It also may be difficult to have "No" be a complete sentence. We may feel we need to offer an explanation. And we can. Or not.
I also think of this between people or in circumstances in which we find that we want to say No, but feel it might hurt another's feelings, or somehow diminish us in another's eyes.
Examples of these:
1) Dating. We've contacted each other, maybe even had coffee, and it doesn't seem like a good fit. So we need to say No to further contact. Do you think women have a harder time with this?
2) People at work are going out to a bar, and we either don't want to go at all, only want to go briefly, are in AA (places), or told our partner we'd be home at a certain time and adding in a trip after work doesn't fit with our prior commitment.
3) Spending time or money or both.
At times, we say Yes because it's the right thing to do, even if we wish we could say No. That's part of what makes this whole topic so tricky. There is no right answer here.
It is healthy practicing saying No, or Yes, or Maybe, and taking the time needed to decide what's best in different situations.
It is also healthy asking for things and being okay with hearing No, or Yes, or Maybe.
It actually makes it safer to ask for and to give to others when the answer is allowed to be authentic. Notice how often your answer is No, or Yes, or Maybe. Notice how come, with whom, and so on. Focus on learning more about ourselves and how we operate in the world.