True repentance demands that a man turn away from sins and from the vanity of this world and turn toward God with all his heart, that he be changed within, and that he become different from what he was before, and so work out his salvation with fear and trembling (cf. Phil. 2:12), and so endeavor to do nothing else but only to please God and so be saved. For if you wish to be in true repentance and so be saved, change yourself and be renewed, and become different from what you were before, and take care for nothing else but only to please God and be saved, and so shall you be a new creature in Christ. For every Christian that wishes to be a true Christian, and not false, ought to be a new or renewed man or a new creature. Do not, then, indulge your flesh, and do not do everything it may desire. It must be crucified with its affections and lusts (Gal. 5:24) when you wish to be a Christian, that is, Christ’s. Much effort and labor is needed, for a man to be changed and to be the good tree that brings forth good fruit. Strive, then, for nothing else but to change, renew, and correct yourself. And pray for this, and sigh often and with all zeal to Christ the Lord, that He Himself might renew you and make you good, for without Him our renewal and correction cannot take place. And when you are renewed inwardly and good, then your outward life and works shall also be good.
– St. Tikhon the Wonderworker of Voronezh and Zadonsk (1724-1783), Journey to Heaven