by knowing how and why works helps for me. so very many people put on false faces only to please others. in most relationships i see, one person is dominate and the other person subordinates themselves to make others "happy" or not to cause pain. fact is, there is constant pain/pleasure, support/challenge, peace/war, and so on in every moment.
when someone makes me upset, then i know that they are fine, it is what i do not like about them that is reflecting back to myself what i do not love about myself i am challenged with. that instantly tells me i need some work done.
while the "serenity prayer" is a nice platitude, it typically only "discharges" an issue, which will ultimately pop back up to deal with, where balancing out both sides of every and all events/people/situations will dissolve them and move us up in consciousness. being able to see both sides and finding the form of what we love is in is one of the main "tricks" to living a mastered life.