Updated: Sep 7, 2021
Humility is no concern to what others think of you, whether they insult you or praise you. You do not base your identity on whether or not others accept you. You do not measure your worth based on other people but your relationship to an infinite God with infinite value. This worth is such a great measure, allowing you to see your absolute personal value despite how low you might be feeling. Though He is so far above you, you have been incorporated into Him. "By whom he hath given us most great and precious promises: that by these you may be made partakers of the divine nature" (2 Pt 1:4).
Self-esteem is reactive because it is a product of a conditioned experience (environment, culture, society) and from what we tend to value. What we tend to value can affect our self-esteem. If we place it in what others think of us, money, or possessions, we devalue our real worth. It is usually emotion-based and often fails to see reality.
There is a joy that comes with being free of nothing to live up to, nothing to prove to anyone (including yourself), no ego to shield from insults or laughs because you know your own "I," ego, self... has inherent dignity and value. The content that comes with knowing the small and ordinary "I" has infinite value; the simplicity and freedom that comes with truly being free to be who you are, ever constant, always governed by one unchanging central attitude, that's humility.
Self-esteem often implies self-judgment and how you feel at the moment. Humility gets you through the lows because you know your real value. You can have humility without self-esteem, but you cannot have appropriate or good self-esteem without humility. It is humility that brings about healthy self-esteem.
Too often, we think of building self-esteem as building up self-love. We need to get away from this. Psychology has often neglected to recognize that self-love is not always good. Those who encourage "self-esteem" as such end up imparting more distress and anguish on their clients, and for parents, their children because they do not know how to help them seek the happiness they desire without simultaneously encouraging a disordered self-love to combat the low self-esteem or depression.
Humility is not masochism, where you find pleasure in negative attention and encourage others to mock you. It is not passivity or accepting insults and injustices reluctantly without protest. Humility is knowing your dignity and standing your ground without compromising that dignity. I am reminded of a story about St. Mother Teresa. While bringing a starving child by the hand to a bakery, and begging for scraps, the baker spat on her. Wiping her face and then holding her closed hand to her chest, she said, "thanks for the gift for me, perhaps something now for the starving child." That is humility.
Stay humble my friends. It is a sure way to happiness and mental health.
I like to remind myself of the importance of humility by praying the Litany of Humility. For Christians, I highly recommend it. We should pray it, and our kids should know it to help fight against excessive self-love (pride).