Chapter 138
How to Compose Your Prayer to the Lord
Memorize several psalms—the ones you like best. And then during prostrations you can read them and from each verse compose your prayer to the Lord. Someone told me about this who began with the beginning of matins—“Have mercy on me, O God”—and did not manage to finish it by the end of matins. This method develops the spirit of prayer more than any other.
(Letter 1458. Vol. 8, p. 198)