In the present moment, you have some kind of pain or difficulty: anger, frustration, disappointment, regret, sadness, hurt.
Notice this difficulty, and see that it’s all caused by whatever story you have in your head about what happened (either recently or in the more distant past). You might insist that the difficulty or pain is caused by what happened (not by the story in your head), but what happened isn’t happening right now. It’s gone. The pain is still happening right now, and it’s caused by whatever story you have about the situation.
Note that “story” doesn’t mean “false story.” It also doesn’t mean “true story.” The word “story” in this context doesn’t imply good or bad, false or true, or any other kind of judgment. It’s simply a process that’s happening inside your head