Whose career am I having?

Possibly nobody's — which is Heidegger's point, and it is stranger than it first sounds.

Das Man, the they, is the anonymous public whose judgment you have absorbed without ever having met it. One goes into that field. One does not leave a role like that after eighteen months. One should be further along by now. The remarkable feature is that it has no members: everyone defers to it, nobody is it, and it still settles what a reasonable life looks like.

Living from it is fallenness, and Heidegger insists this is not a moral failing. It is the default and largely unavoidable — you cannot invent your own standards for everything and still get through a Tuesday. What he wants is that you notice it, because a life can be entirely composed of reasonable next steps and belong to no one.

Add thrownness: you did not select the era, the economy or the family that made this path obvious. You began in the middle of a story already running.

Authenticity is owning the thing as yours rather than as what one does. Notably, it tells you nothing about what to choose — which is why it converts into career advice so easily and so badly. It is a change in ownership, not in direction.