When the love of God has taken possession of a soul, it produces an insatiable desire to work for the beloved; insomuch that however many and however vast the works which she does, and however prolonged the duration of her service, all seems nothing in her eyes, and she is afflicted at doing so little for God ; and were it permitted her to die and consume herself for him, she would be most happy. Hence it is that she esteems herself an unprofitable servant in all that she does; because she is instructed by love to know what God deserves, and sees by this clear light all the defects of her actions, and finds in them motives for confusion and pain, well aware how mean is all that she can do for so great a Lord.
--St. John Chrysostom