My grandma used to tell me to pick my battles. She meant regarding life, relationships, work, etc. In other words, don't waste your time arguing over things that don't matter. Sounds silly and simple but it's great advice that is hard to actually follow.
I saw a quote from Buddha a few weeks ago that said "Holding onto anger is like drinking poison and expecting the other person to die." That really hit home for me. I know I have wasted unnecessary time holding anger inside and it truly just wastes your life. It is incredibly freeing to allow yourself to forgive and move on.