Feeling like I have little control over my life

I know I can't control absolutely everything that happens in my life but I'd like to be able to control the things I can. Unfortunately, I can't.

I've always been a people pleaser, which doesn't help. I find myself more prone to wanting to lash out because of it, I've been in the same position for so long and my inability to assert myself or stand my ground doesn't help.

I would sooner let someone mistreat me than confront them because it's safer to just let them. I know I'll come away from it feeling more angry and resentful but I don't feel safe enough in the moment,

I'm intrigued as to what has helped people (if there is anything that has). Maybe there's something I've not dug deep into enough.