This phrase is reminding us to focus on our inner selves rather than our external environment. It means that the things that you have done in the past and what you will do in the future are much less significant than the person you are inside. It stresses the importance of self-confidence and how our inner strength, character, and beliefs are the most important things in life. It suggests that it is only by looking within and uncovering who you are and what you are capable of achieving, that you will lead a successful and meaningful life.