The Hebrew word for "restoreth" means "to return, to bring back." This happens in several ways as God works with his chosen ones. This restoration comes from God: "HE restoreth my soul." We cannot restore our own souls from sin and backsliding. God must be the author as well as the finisher of our faith.
He restores us from our sins in salvation. We all fell in Adam, turning away from God in disobedience. We all fell into sin: the practice of sin and the condemnation of sin. Notice the following scriptures.
Rom. 5:12 Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned:
John 3:18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
In our sinful condition, we need salvation by grace which comes only from God. It is by grace that we are saved: Eph. 2:8 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:
He restores us from backsliding. Jer. 3:6 The LORD said also unto me in the days of Josiah the king, Hast thou seen that which backsliding Israel hath done? she is gone up upon every high mountain and under every green tree, and there hath played the harlot. So many in our own day have turned from their Lord to the beggarly elements of the world: Ga 4:9 But now, after that ye have known God, or rather are known of God, how turn ye again to the weak and beggarly elements, whereunto ye desire again to be in bondage? Either true believers or simply professed believers have turned their backs on the Lord for these beggarly elements and have turned to the world for their satisfaction. From this the true believer can be turned and shall be restored when the grace of God is effective in his life.
Jer. 3:22 Return, ye backsliding children, and I will heal your backslidings. Behold, we come unto thee; for thou art the LORD our God. Jeremiah prophesied much concerning backsliding Israel. They are encouraged to "return." This is the same word that is used in Psalm 23:3 that is translated "restore." It is God who turns us, pricks our hearts, and carries us back to himself through his word even as he did Peter when he denied the Lord.
So, dear believer, keep yourself under the preaching of God's word, for it is God's word through which God will restore your soul, and it will be restored to the blessedness of the Savior and the sweetness of his communion. We dare not return back into the world once we have been restored. Once should be a sufficient number of times to teach us the difference between being backslidden and being in God's constant care and assurance.
He will restore us from weakness. When our bodies get weak and we cannot do what we once did (and many who read this have already experienced this), it is God alone who can restore the soul in these times, draw us above the strife of heart that is brought by the overwhelming calamity of disease and sorrows of life. As our hearts get weaker and weaker and our bodies diminish their usefulness, God is there to restore that body to that which his purpose claims.
It may not be God's will that you or I will return to our former youthful energies, but God will nonetheless restore our souls, not only in our confidence that God is working in us both in strength and weakness, but he will ultimately bring us to himself through his Son, Jesus Christ. 1 Peter 3:18 For Christ also hath once suffered for sins, the just for the unjust, that he might bring us to God, being put to death in the flesh, but quickened by the Spirit: He will bring us to bodily death and quicken us through his Spirit so that we may experience the ultimate of God's blessings and entertain a wonderful reception in Heaven for all who believe. This is the greatest and most splendid restoration.
So brighten up your corner by believing in God, that he will restore your soul. He is our Shepherd, and this is one of his duties as our Great Shepherd.