Often, we say yes when we want to say no just to avoid the experience of discomfort. When we respond in ways that fail to honor our own boundaries we usually delay, rather than completely avoid, discomfort. It is inevitable and your relief will only be temporary. The choice to avoid discomfort now will almost surely lead to discomfort later.
It has been said - She who trims herself to suit everyone will soon whittle herself away.
What can you do instead? Search within for the courage and patience to sit with your discomfort. Learn not to judge or avoid it. Let it instruct you. Decide to notice how it shows up. What is it's feeling, location, shape, movement? How do you experience the pressure of it? What voice does discomfort use? What stories does it stir up?
And there will be stories. Have responses ready for your inner critic. That's where the stories usually come from. Make those responses compassionate and kind - no matter how savage your critic tries to be. Stand firm in defense of yourself - be your own advocate.
If you can't stand in your own defense yet, ask for help. Write down everything the critic throws at you and get someone you trust to help you find evidence to the contrary. Why not assemble your own defense team? In time, this is how you will come to honor your own boundaries, even when it feels uncomfortable.