Those who desire to free themselves from [sin] ought to pray not merely from time to time but at all times; they should give themselves always to prayer, keeping watch over their intellect even when outside places of prayer.
When someone is trying to purify gold, and allows the fire of the furnace to die down even for a moment, the material which he is purifying will harden again. So too, a man who merely practices the remembrance of God from time to time, loses through lack of continuity what he hopes to gain through his prayer. It is a mark of one who truly loves holiness that he continually burns up what is worldly in his heart through practicing the remembrance of God, so that little by little evil is consumed in the fire of this remembrance and his soul completely recovers its natural brilliance with still greater glory.
-St Diadochos of Photiki