When you are in prayer, do not ask to be entirely free of mental wandering, which is impossible, but seek to wander following something that is good. For even pure prayer consists in a wandering which follows something – but this wandering is excellent, seeing that the search for something good is excellent. Wandering is bad when someone is distracted by empty thoughts or by pondering on something bad, and so he thinks evil thoughts when he is praying to God.

A seventh-century bishop retreated to the wilderness, lived for years as a hermit, and still struggled to focus while praying.