Saying NO is so difficult...especially when you are put on the spot with no advance warning.
I used to be such a "yes" person....and then I'd be kicking myself in the butt for agreeing to do something, go somewhere, make something, lend something...you name it.
Now, I'm a NO person. I first say NO to just about anything....cos I can always change my mind later, or say plans have changed and I'm now available