The Path to the Cessation of Suffering
The Fourth Noble Truth, Magga, is actually more complex than the first three truths and is part of a much longer teaching known as the Noble Eightfold Path. Fundamentally, it can be explained simply as a set of three pillars, each of which is necessary to cease suffering.
Ultimately, Wisdom (Prajna), a gathering of skillful experience, is the ability to recognize the goal—the cessation of suffering. According to the Buddha, the collection of wisdom is not possible without the Mental Discipline (Samadhi) to commit to a life of Ethical Conduct (Sila).
The first three truths basically noted that suffering stems from a self-inflicted desire to control what you actually have no control over. For writers, it may be a desire to control publishing. For athletes, it may be a desire to control a judge or referee. For students—a desire to control a subjective grade.
What the Fourth Noble Truth is saying is that a person needs to be able to recognize the source of suffering in their life (wisdom) and that mental discipline—discipline here means “teaching”—and ethical conduct will enable that person to see this and adjust accordingly.
Again, the point here is not to not have goals. The point here is not to base your happiness or mental well-being on outcomes that you do not control. I have no control over how the Boston Red Sox perform—therefore, I am not sad when they lose. I don’t have control over who likes or dislikes these posts on Buddhism, but writing about them helps me understand them better. I would certainly love to publish a book, but I refuse to tie my happiness to acceptance or rejection—I simply write to the best of my ability and that makes me happy.