“He who at dinner has many different foods eats much and with pleasure, whereas he who uses every day the same food not only eats it without pleasure but sometimes perhaps even feels repelled by it. So it is in our state. In psalmody and prayer do not bind yourself, but do as much as the Lord gives you. Do not abandon reading and interior prayer either. Some of one and some of the other and so you will spend the day pleasing God. Our perfect fathers did not have a fixed rule, but during the course of the whole day they carried out their rule.”

St. Barsanuphius the Great, On the Prayer of Jesus 56