From Robert Greene's Mastery — which he calls, in his own words, "the most important of all the books I have written" and the one he recommends above all others for people in high school — the central task of that life stage is discovering your "life's task": what you were meant to accomplish, your goals, your vocation. Greene treats this as inseparable from self-knowledge — understanding "who you are, what makes you different" isn't a separate exercise from finding your vocation, it's the same inquiry.
Greene's practical framing: have a rough sense of the career direction you're headed toward while still holding a spirit of adventure — direction and openness aren't opposed. This pairs with Attitude as Self-Fulfilling Prophecy (Excitement vs. Fear): an excited, open attitude gives you the room to explore and discover the life's task in the first place, while a fearful one forecloses the search before it starts. Same author as Seducer Archetypes (Greene's Typology) (Robert Greene).
Robert Greene frames the life's task as the essential first phase that must precede apprenticeship and craft mastery, not just a step alongside it. Every person carries a unique seed shaped by their unique DNA, upbringing, and early experiences; per Greene, "your destiny, your fate in life is to know what that seed is, to know who you are, what makes you different from everybody else, and to cultivate it." Skipping this discovery renders the apprenticeship phase miserable or misdirected, since the person ends up pursuing work unsuited to their nature.
Greene insists the process cannot be rushed: it is a slow, effortful excavation, not a single realization. He says it took him 18 years to discover the kind of books he wanted to write, and that he had no professional success until age 38-39 — "quite a bit of a failure" until then. His recommended starting method is concrete and low-altitude rather than abstract soul-searching: journal over an extended period, tracking what you love and hate down to basic preferences (food, drink, clothing), gradually surfacing what makes you different from everyone else.
He frames this discovery as fought against a headwind: modern culture (social media, constant externally-oriented signals) makes hearing your own inner voice harder than at any point before — "you can't hear yourself anymore." See Impulse Voices (Abraham Maslow) for the mechanism by which that inner voice gets drowned out, and Five Frames of Intelligence (Howard Gardner) for a diagnostic model of the natural "grain" of intelligence the life's task discovery is meant to surface. The life's task and craft mastery are also not fully separable in Greene's account — see Mastery of Self Through Craft.