Being angry and holding resentment (to re-think, re-feel or re-hash things) against others is like giving people rent-free space in our brains while they (the other people) are sleeping, and being aware of that is at least part of my motivation for trying to live anger-free or at least free of being controlled or driven by anger. For myself, returning feelings of anger come from me thinking about me rather than considering the other person's reality. There might not always be anything I can do to help satisfy the other person's need or desire behind his or her actions that angered me, but I can at least come to terms with the fact she or he was usually just making his or her own best effort at life.