I see that people pleasing is fast becoming a menace in the lives of a lot of us. It takes just one resolution that'll stick to our brain to help us stop. I have tried it, and I can tell you that it works.
Learning to say NO and sticking with it has never killed anyone. Rather, taking responsibilities beyond capacity kills instead, and I don't mean it kills to heaven, rather, I mean that it kills aspirations, goals, and one's ability to think without putting other people first.