When the love of God obtains the mastery of a soul, it produces in it an insatiable desire to labor for the Beloved; so that, though it may perform many and great works, and spend much time in His service, all seems nothing, and it constantly grieves at doing so little for its God. . . . And as it feels that its work is very poor to be offered to so great a Lord, it is at the greatest distance from vain-glory and presumption, and from condemning others. -St. John Chrysostom
St. Vincent de Paul was equally unwearied and insatiable in laboring for God, and rendering himself acceptable in His sight, nor did he think he had ever done enough for so great a Lord. In imitation of the Apostles, he forgot the good works which were behind him in the past, and put all his thoughts and efforts upon advancing daily in God’s service.
St. Charles was remarkable for this virtue. As long as he lived, he had an insatiable desire to honor God, and to spread and promote His worship, which spurred him on to labor without weariness. He seemed to grow fresher every day, under labors that succeeded one another without intermission. While those who attended him were often prostrated by fatigue, he never gave the least token of it, as if labor were rest and recreation to him.
Text from A Year With the Saints (New York: P.J. Kenedy & Sons, 1891).