Flogging a dead horse is a phrase that implies wasting time on an action that will not bring any results or change. There are several synonyms for this term, including beating a dead horse, banging your head against a wall, pouring water into a broken glass, going around in circles, and spinning one's wheels. All these expressions depict the futility of an action that leads to no progress. It is crucial to recognize when one is flogging a dead horse to avoid wasting time, effort, and resources on a lost cause. Instead, one should seek new, productive ways to achieve their goals and succeed.