Adulthood:

Have you ever done something you hated for years? Something that bored you to tears? Something that made you think of suicide whenever you drove past the graveyard on your way home on a dreary evening?

And then you felt relief, when you realized you could just quit instead of rising before dark to repeat the same day tomorrow. But you thought how long could you possibly survive without an income from doing that boring something?

That's how you know you're an adult. When you've been doing something you hated for years.