The difference is perspective. You're right that grind is unavoidable, but it requires a big-picture perspective that the work is still valuable and therefore worth completing. If the wider circumstances have changed, then grinding because success demands grinding belies the fact that success will no longer be achieved through grinding. The key, in the beginning, is to attempt to reduce the amount of grinding that will be necessary by reducing scope as much as possible for what is needed to ship; the less grinding you need, the more likely you are to ship, and the more likely you are to continue to ship in the future.