We should recognize that, when Jesus presents meekness in Matthew 5:5 as a highly desirable quality, He prefaces it with "Blessed are the poor in spirit" (verse 3) and "Blessed are those who mourn" (verse 4). He places it within a context that contains qualities that are similar to meekness. Alexander MacLaren writes in his comments on verse 5, "[Meekness] is the conduct and disposition towards God and man which follows from the inward experience described in the two former Beatitudes, which had relation only to ourselves" (Expositions of Holy Scriptures, vol. 6, "St. Matthew," p. 130). In other words, meekness is the active fruit of the other two, but whereas being poor in spirit and mourning are both internal in operation, meekness is both internal and external in its execution in one's life. Though this is not a complete description, it lays a good foundation.
Godly meekness is impossible unless we first learn a just and lowly estimate of ourselves. We must become poor in spirit. We do this by coming before God in deep penitence and with a clear knowledge of the vast difference between ourselves and what He is and what He means us to be. Paul says in Romans 12:3, "For I say, through the grace given to me, to everyone who is among you, not to think of himself more highly than he ought to think, but to think soberly, as God has dealt to each one a measure of faith." While pride destroys self and others, humility serves and builds.
Mourning springs from a sense of sin, from a tender conscience, from a broken heart. It is a godly sorrow over our rebellion against God and hostility to His will. It is the agonizing realization that it was not just sin in general but our own sins that nailed Christ to the stake. Notice that Matthew 5:4 is in the present tense, meaning that mourning is not confined to our initial repentance—it is a continuous experience. The Christian has much to mourn. If his conscience is kept tender by an ever-deepening discovery of human nature's depravity, his sins—both of omission and commission—are a sense of daily grief. Paul writes in Romans 8:23, "[W]e ourselves groan within ourselves, eagerly waiting for the adoption, the redemption of our body." He adds in Romans 7:24, "O wretched man that I am! Who will deliver me from this body of death?"
At the same time, this does not mean a Christian lives his life with a hang-dog expression and attitude, or that he lives his life feeling that he is a dirtbag or sleazeball who is still mucking around in a moral septic tank. A Christian is also forgiven, cleansed, and justified by the blood of Jesus Christ. He has access to God the Father, is the apple of His eye and has an awesome hope before him. He has the Holy Spirit in him. He is a child of the great Creator and looks forward to being resurrected and inheriting God's Kingdom. Christ died for him, and this creation exists for his perfection. A Christian has many reasons to feel a sense of exultation for what has been provided for him. An awareness of sin—as long as it is not allowed to become obsessive—will help him continue in a humble frame of mind by keeping pride in check, tempering his judgments, and allowing him to accept the events of life in a spirit that produces great contentment.
These qualities are produced when, with God's help, we rightly measure ourselves against the right standards—God and His law—rather than each other, and discover how much we owe to God's merciful grace. Anyone thus convicted and then forgiven and cleansed by Christ's blood is in the position to produce godly meekness.