Humility is the robe of the believer; we are to adorn ourselves with it daily. All acts of humility apart from Christ are nothing more than appearances without substance, upon close examination, it will prove to be nothing but pride in disguise. The reason being is that the unconverted person has no spiritual life and disposition of heart to be humble for Christ's sake. Therefore, any attempts at godly virtue apart from Christ are filthy rags in the eyes of God.
However, for those who are born again, it is the principle virtue of the regenerate heart. It is the virtue from which all others are to flow. The Lord Himself taught us this truth by example. He said, "learn of Me, for I am meek and lowly in heart" -Matt. 11:29. The Apostle Paul wrote, "Walk in a manner worthy of the calling to which you have been called, with all humility and gentleness, with patience, bearing with one another in love" -Eph. 4:1-2. These are not motions we are to perform. Nor are they outward masks that we put on Sunday morning. The very attitude of our heart ought to be one of humility.
Humility is an act of selfless love, putting the wellbeing and the good of others before your own. I understand this is not our natural reaction, by nature we are prideful, selfish people. Pride is the reason why so many people demand their way. The type of character I'm talking about is supernatural and can only be lived out in Christ.
God is the moving cause of humility. The heart of the Lord gives to His people enlightened eyes so they can properly see themselves as recipients of the unmerited favor of God. Therefore, humility pours forth from a right judgment of one's self. The humble acknowledge that they are made of dust and reside in weak, sin-contaminated bodies. Without Christ, they realize they are blind, poor, miserable naked, wretched, depraved, and by nature children of wrath. They know they are worthy of nothing but death. But God, by grace through faith in Christ alone has saved them and changed them. Now they see how wrong it is to elevate themselves, pretending they are worthy and demanding their way. Now, by means of grace, they observe others as more important than themselves.
A final important note, humility is a work of grace in the heart of a believer by the Spirit of God. However, the believer also has the responsibility to learn humility. Often, it does not come forth spontaneously, or at least I find this to be true in my life. Cultivating humility means you have to be willing to examine yourself daily in light of God's Word. Second, you must look to the cross daily. The cross on which Christ died is the greatest teacher of humility. You will definitely find yourself complaining less. Third, look to the blessings and benefits of God. They will humble us when we consider our ingratitude, but they will also encourage us in the fact that indeed we are blessed children of God.