I am a firm believer in persistence and determination. Many people give up just before things are about to break their way. However, it never makes sense to go off a cliff simply because it is there. Not every strategy is wise and not every course of action is worth continuing. You need to pay attention to the signals the universe is sending you. Trends either move up or down. They rarely remain flat. Sometimes the objective evidence indicates you should try something different.
Many leaders I know struggle initially with the idea that the most value they bring to their company or organization is their ability to think not act. Of course, thought without action is meaningless. However, the top people in any organization need to regularly step back and reflect on strategic implications, priorities, etc.