The promise of God's blessing extends to those who grieve with godly mourning. Remember, the Greek word for blessing means "happiness." It might seem ironic that God promises happiness to those who are in mourning, but that is indeed the assurance to those who mourn, for they will be comforted.
First look at the what of the assurance that godly mourners will be comforted. This term "comfort" comes from the Greek word parakaleo, which comes from the same word that serves as a title of the Holy Spirit, "Comforter." 2 Cor. 1:3 declares that God is the God of all comfort. Christ is the Christ of comfort. And the Holy Spirit is your comforter. You have the entirety of the triune God to deliver to you comfort in need. And what it literally means is "helper." In the context of godly sorrow, God promises you help in the place of your sorrow, which is your spiritual poverty. To be comforted means to receive the help of God, whether it be in the Father's provision, the Son's presence, or the Spirit's persuasion.
Next, look at the when of the assurance that godly mourners will be comforted. The word says "will be" or "shall be" comforted. Like all of God's promises, this one won't be fully and finally realized until life ends. After all, Revelation 21:4 says that God, in eternity, will "wipe away every tear from their eyes; there shall be no more death, nor sorrow, nor crying; and there shall be no more pain, for the former things have passed away. (Rev. 21:4)"
But know this: this promise given is not only for eternity. It is the promise to be delivered as you obey. As you continue to mourn over sin, you will continue to be comforted in this life.
This is the main determiner between conviction over sin, and condemnation over it. The enemy condemns you for your sin in an attempt to separate you from the Lord who loves you. But the Holy Spirit convicts you of your sin, so that you may mourn over it, and receive the blessing of being comforted.
This is the key to godly mourning. In its essence, mourning over your sin is not about you, and it is not about your sin. It is about God. Look again at what Job and David declared: their brokenness wasn't about what they did. It wasn't that they got caught. It was that they offended, hurt, defamed, disregarded God in all His love and holiness.
In this matter, spiritual maturity is not necessarily a matter of sinlessness (though you should hope to see sin less and less present in day-to-day living), but instead it becomes a matter of increasing awareness of sinfulness. Does this mean you need to live your existence as an unhappy sackcloth and ashes person? God's word says this -- Your sins are ever before you (Ps. 51:3), but if you confess your sins, God is faithful and righteous to forgive you of your sins and cleanse you from all unrighteousness (1 Jn. 1:8-9).
God's grace is greater than all man's sins, and for those who mourn over that sin, through His grace, you are able to rejoice in the Spirit because of the comfort He offers (Rom. 5:1-2).
All that remains is the how of mourning. If the only way to be poor in spirit is through godly sorrow over your sin, it is important to know how to do just such a thing. Here are some helpful suggestions: