But reframing only goes so far. "No" is still a hard sentence to say, and like any skill, it needs practice. So how do you start?
"Do you need a glass of water?"
"No. Thank you, though."
"I love this book! I think you'd like it too. Do you want to borrow it?"
"I appreciate the offer, but no."
Once you're used to saying "No" to smaller things, try with something a little bigger.
"Can you give me a ride to work today?"
"No, got a doctor appointment. Sorry."
Practice saying "No" when you feel it, and it'll get easier to give your "Yes" meaning.
Enthusiastically choose your life.