Just browsing a few blogs, and encountered one that seems interesting:
In it, Rob Rufus defined what humility is according to his thinking:
A: It is not gained through apology and self-deprecation. Humility is the revelation of grace that fills your inner life with security: with such a sense of significance: validated by God’s Love for me ... therefore I am significant, secure and valuable—I don’t have to prove anything! I don’t have to boast or compete with people or be jealous because I feel so significant and safe and secure because I am accepted in the Beloved.
I think this is very interesting. We often think of humility as thinking of ourselves insignificant, unworthy compared to other people and God's grace. But here Rob gives another viewpoint: We can be humble if we realized that we are already received the grace, and nothing we or other people do to us can reduce our significance in the eyes of God.
So there's nothing to prove or boast about, because everything is from grace.