Stop judging people. Then they won’t piss you off as frequently.
Take coworkers, for example. We don’t choose them. We don’t really know them. We may become friendly, but we generally move on to the next people at the next job, don’t we? We don’t know their lives, their struggles, their victories. Who are we to judge them?
Let go, simply accept, and you will be freer of anger and resentment.