Now no chastening seems to be joyful for the present, but painful; nevertheless, afterward it yields the peaceable fruit of righteousness to those who have been trained by it. (Hebrews 12:11, NKJV).
The goal of divine chastening, like that of parental chastening, is godly sorrow leading to true repentance. Over time, and applied consistently, or in God's case, applied perfectly in every way, it yields the peaceable fruit of righteousness to those who have been trained by it.
Not all pain in the life of a believer is indicative of the Father's correction, for such things come to the Christian for other reasons, as well. But make no mistake, when the Lord disciplines His child, it hurts. It is supposed to hurt, for pain is the great attention getter and behavior changer. Without it we would be, in our sinful state, the very devils of Hell.
So while no chastening seems to be joyful for the present as it is being inflicted, because of the godly result, we are not to despise the chastening of the Lord, nor be discouraged by it. In fact, if we subject ourselves to Him in every way, not just peace, but joy is ours in Christ. It is a fair trade. It is the only transaction that enables escape from eternal damnation.
Chastening by the hand of our loving Father, like discipline by the hand of a loving parent, is ultimately a cause for rejoicing, for it says we are His legitimate sons and daughters; that He cares for us too much to let us go our own way uncorrected, knowing that the end of those things is death.
So what is that peaceable fruit of righteousness? Why is it so desirable?
All human action bears some kind of fruit. Most of it, especially that grown in our natural state, is rotten right from the start. The fruit of sin is the opposite of nourishing. It is poison for which there is only one antidote. Christ. In contrast, the fruit of righteousness gives life, and beyond that, peace. Peace from guilt. Peace from the fear of strife or retaliation. The peace that comes from following the very Prince of Peace, not because of who we are, but because of who He is. It is peace that comes from pleasing God through faith. It is peace that passes all understanding.
Being right with God is the only true safety. There is NO security in the world without God, and no rest, for nothing but evil is guaranteed without Him - the evil of men, or circumstances, or the ultimate evil of death itself. These are the defaults, rife with loss and pain and suffering - for even the most prosperous sinner is on the inevitable road to the grave, and the judgment that comes after. Again in contrast, the duly chastened child of God can have this eternal consolation - that whatever evil befalls in this life, it is only for a little while in comparison to the unimaginable blessing of the life to come.
Righteousness itself comes with its own inherent peace precisely because to be righteous must include love, joy, long-suffering, kindness, goodness and self-control. It is not mere intellectual correctness or factual accuracy, it is a bone-deep, cell-deep, soul-deep state of being that is a reflection of the Son of God Himself. For our sin He gives us His righteousness, and we become like Him.
God's righteousness and peace are desirable because following His lead takes the guesswork out of living. His children know what path to take, what choice to make, and how to respond to whatever life throws at us. There is no such thing as situational ethics or nuanced choice. There is no refuge in deceit. There is no uncertainty as to whether we keep our word, or decline to take advantage of someone. There is a safeguard against temptation, which if we submit, protects us from the dire consequences of succumbing to our own sin. It is a shield and hedge of protection - a strong tower from our enemies. It is shelter beyond anything the fallen world has to offer.
Now a final point.
The righteousness of God is not an odious catalog of do's and don'ts. It is not a self-congratulatory checklist that we can tick off at the end of the day, or on our deathbed, patting ourselves on that back assured that God now owes us something. Jesus made that perfectly clear in His parables regarding the unprofitable servant who by doing what is right, does only the bare minimum of what is already expected and required.
No, the righteousness of God is not a striving, but a surrender. It is the laying down of your own debased sovereignty, and yielding to His. It is the knowing what is right and true from His word, and simply allowing Him to empower you through His Spirit to walk in His ways, rather than in your own twisted ones. It is obedience through love, not fear.
Be assured that self-righteousness of any kind is a delusion. If you are the one on the throne of your life, you are inevitably an evil ruler, despite whatever appearances otherwise. You cannot do what is right without Him, for there is none good, no not one.
So discard the illusion. Submit to His correction and chastisement, and be conformed into the image of His Son who died that you might live.
Then, and only then, will you even begin to taste the peaceable fruit of righteousness.
