A constant remembrance of God
Be encouraged! Take up prayer more readily and continue without interruptions—and you will soon achieve your desired goal. Soon a reverent attention to the One God will be established, and with it, inner peace. I say soon, not now, or in a day or two. Months may be required, sometimes, even years. Ask the Lord and He will help.
From The Letters of St. Theophan the Recluse, Letter 43