You cannot fake this one out. You know every promise you made and broke, every standard you said you held and didn't, every time you said one thing and did another. The inner record is always accurate. Self-esteem is not how you feel about yourself in a general mood. It is the honest accounting of whether the person you claim to be matches the person you have actually been. You build it the same way you build any reputation: by doing what you said you would, repeatedly, when no one is watching.