St. Theophan the Recluse (d. 1894) writes:
May God bless you.
But with the habit of reciting this prayer orally, unite remembrance of the Lord, accompanied by fear and piety.
The principal thing is to walk before God, or under God’s eye, aware that God is looking at you, searching your soul and heart, seeing all that is there.
This awareness is the most powerful lever in the mechanism of the inner spiritual life.” (The Art of Prayer, pp 89-90)