According to Seneca, the Greek word euthymia is one we should think of often: it is the sense of our own path and how to stay on it without getting distracted by all the others that intersect it. In other words, it’s not about beating the other guy. It’s not about having more than the others. It’s about being what you are, and being as good as possible at it, without succumbing to all the things that draw you away from it. It’s about going where you set out to go. About accomplishing the most that you’re capable of in what you choose. That’s it. No more and no less. (By the way, euthymia means "tranquillity" in English.)
It's time to sit down and think about what's truly important to you and then take steps to forsake the rest. Without this, success will not be pleasurable, or nearly as complete as it could be. Or worse, it won't last.
...So why do you do what you do? That’s the question you need to answer. Stare at it until you can. Only then will you understand what matters and what doesn’t. Only then can you say no, can you opt out of stupid races that don’t matter, or even exist. Only then is it easy to ignore "successful" people, because most of the time they aren’t—at least relative to you, and often even to themselves. Only then can you develop that quiet confidence Seneca talked about.
From Seneca's essay "On Tranquility" (via Dialogues and Essays):
For a long time now, Serenus, I assure you, I have been asking myself in silence to what I should liken this mental state of yours, and the closest parallel I can find is the condition of those who, having gained release from a lengthy and serious illness, are sometimes affected by feverish fits and minor disorders, and, despite being freed from the final traces of these, are still troubled by feelings of doubt and, now in full health, hold out their wrists to their doctors, complaining unfairly about any feeling of warmth in their body. With these people, Serenus, it is not that they are not quite well physically, but that they are not quite used to being well, just as even a tranquil sea will show a ripple or two, especially when it has subsided after a storm. Accordingly, you have no need of those harsher measures that we have already passed over, that of sometimes opposing yourself, of sometimes getting angry with yourself, of sometimes fiercely driving yourself on, but rather of the one that comes last, having confidence in yourself and believing that you are on the right path and have not been sidetracked by the footprints crossing over, left by many rushing in different directions, some of them wandering close to the path itself. But what you long for is a thing that is great, supreme, and very close to the state of being a god: to be unshaken.
...................This constant state of mental composure the Greeks call euthymia, on which Democritus has written an outstanding treatise; I call it tranquillity; for it is unnecessary to imitate and reproduce words in Greek lettering: the actual thing under discussion needs to be designated by some name which must have the force, not the form, of the Greek term. Our enquiry, then, is directed at how the mind should proceed always on a steady and favourable course, may have good intentions towards itself, and may take pleasure in regarding its state and have no interruption mar this joy, but remain in a peaceful condition, at no time raising itself up or casting itself down: this will be tranquillity.
Related previous post: Areté
Related link: Apatheia vs Ataraxia: what’s the difference?