I don't think Walter is implying anything about how common or uncommon this is. His core insight seems fairly objective and plausible to me: "...your chances for happiness are increased if you wind up doing something that is a reflection of what you loved most when you were somewhere between nine and eleven years old". I.e. if you do end up being lucky and wise to do something as a profession closely related to what you *loved* doing when you were ~11 , because you end up spending time doing what you love (and equally importantly not spend that time doing something that sucks up energy) you increase your chances of being happier.