Marcus Aurelius, the great Stoic, simplified it a little further. In his own words, “The happiness of your life depends upon the quality of your thoughts.”
To Plato, for example, happiness was deeply connected to morality, and in order to achieve it, he believed that we would have to uphold four different virtues: wisdom, courage, moderation, and justice.
It’s true that there is no substitute for talent. But talent without hard work is nothing, nothing at all. It flares briefly and explodes in the grey world, and afterwards we are not sure if it was anything at all.