If every habit changed gradually, when would you say you had become somebody else?

There is no line to cross. Change a habit at a time and no single change makes you a different person, and yet after fifteen years the person is different, with no moment anyone could point to. Identity is continuous even when it ends up somewhere entirely else, which is why becoming someone new rarely feels like an event.

If you want to change, this is good news, because it means no dramatic transformation is required or available. It also means drift happens the same way. Looking back five years and asking what has quietly changed is worth doing occasionally.