I Am Learning Self-respect, Self-care, And Self-love

I Feel like I am in a constant battle between my needs and others. There are many times in my life where I should step away from a certain situation that I'm sure will effect me negatively but I don't because I know what is expected of me. I feel selfish whenever I have to put my needs and health first. I need to always put everyone first and think of myself last. I've never been able to be in the position of just worrying about my personal needs. And I think this has made me into somewhat of a pushover and an unnecessarily overly polite person. My biggest struggle is being more assertive and saying how I truly feel.