Without principles, self-discipline is impossible.
You don’t have an identity if you don’t have a principle that shapes and defines your life. You should live by a set of principles that define your boundaries and keep you out of trouble in an unfamiliar terrain.
A principled lifestyle could speak for you when and where it really matters because people usually attach a character to a position. And a strong character that is often sought to fill positions of leadership, is built on effective principles.