That’s why you won’t say no in the first place. If you can see worth in yourself then you will be able to see worth in your opinions and then it will be easier to say no because it will be consistent with your beliefs. Now I know that sounds way easier than the reality but you have to start somewhere, maybe just find a few things where you were right, where you felt good, where things clicked for you. Tap in to those feelings and then work out ways to recreate them with new experiences. It’s your life, reclaim it.