Pray without Ceasing

Have you ever wondered what St. Paul means when he encourages us to "Pray without ceasing" (I Thess. 5.17)? Consider this understanding of that imperative by an Orthdox writer:

Usually in the Holy Scriptures, the word always is used in the sense of "often." For instance, "The priests went always into the first tabernacle at certain fixed hours, not that they went there unceasingly by day and by night; they went often, but not uninterruptedly." Even if the priests were all the time in church, keeping alight the fire which came from heaven, and adding fuel to it so that it should not go out, they were not doing this all at the same time, but by turns, as we see from St. Zacharias: "He executed the priest's office before God in the order of his course' (Luke 1. 8). One should think in the same way about prayer, which the Apostle ordains to bedone unceasingly, for it is impossible for man to remain in prayer day and night without interruption. After all, time is also needed for other things, for necessary cares in the administration of one's house; we need time for working, time for talking, time for eating and drinking, time for rest and sleep. How is it possible to pray unceasingly except by praying often? But oft-repeated prayer may be considered unceasing prayer.

Source: The Art of Prayer: An Orthodox Anthology. Compiled by Igumen Chariton of Valamo. Edited by Timothy Ware. (Chatham, Kent: Machays PLC, 1997), 49.