In a time where self-determination AND helping your fellow human AND following your core values AND fulfilling obligations collide and sometimes conflict, something's got to give! People who are overworked and spread thin try desperately to learn to say "no" but feel as much pressure to say "no" as they do to say "yes" to everything!
"No" is a complete sentence, sure. But wow, can it be an uncomfortable one. What if it's just not your style to be that blunt? Why is it so hard to say no?
Chalk it up to societal conditioning, how you were raised, the generation you were a part of, or simply personality, the reality is that the degree of difficult in learning how to say "no" is incredibly high for some. And all it does is add more pressure and give people yet another reason to beat themselves up.
This is very unfortunate because most of the time, it's totally unnecessary. There are TONS of alternatives to "no" - how about:
"Not right now" or "Not yet" or "Let's talk next month."
"Yes, absolutely - if XYZ conditions are met to make sure it all goes well."
"Let me think about it."
"I'd say yes except for XYZ - can we talk about how to address that?"
I can go on. The point is to give yourself some breathing room. Use the Eisenhower Matrix to help organize what's already on your plate and determine what would need to be in place to accommodate something new.
It takes practice to find the alternatives to "no" that would work for you, but they definitely exist! Practice to see what feels right.