One thing that made me determined to change my own people pleasing habits and change how I saw them was being on the other end of it.
My aunt is a chronic people pleaser. People think she’s so nice, kind and lovely - and in many ways she is - but she will often say yes to things and then resent it or bitch to other people about how much she’s done for so and so or how much she’s “put up with”. I found out the hard way that she resented me bringing my dog with me when I visited because he shed so much - I’d asked, she’d always said yes and refused my offers to help clean up/vacuum afterwards. But she told my cousin how much mess my dog made and how much she hated it when the dog came and she didn’t understand why I couldn’t leave him at home. Causing my cousin to think I was being terribly inconsiderate to my aunt and being selfish. My cousin had a go at me and I didn’t understand why, because my aunt had always seemed so accommodating.
The cause of this situation was that my aunt said yes to something when she meant no. And the outcome in the end was upsetting for everyone - my cousin and I fell out, my aunt felt guilty, and as a result was even more afraid to say no to people! I don’t visit her now, because I have no idea what the rules are, fundamentally I don’t feel safe around her because her chronic niceness actually makes her dishonest. Once I’d realised in my own head that people pleasing does not = being a nice person, it actually = dishonesty, I fundamentally couldn’t continue to do it.
Of course there were reasons why I had these habits in the first place - there was childhood trauma and undiagnosed neurodiversity, I was a parentified child. Often these sorts of patterns develop because of trauma and it’s important to be compassionate towards that, but we also hold ourselves accountable as adults for changing said patterns and becoming who we want to be.
Good luck. You can do this, it is possible.