Why are you cast down, O my soul, and why are you in turmoil within me? Hope in God; for I shall again praise him, my salvation and my God. (Psalm 42:11 ESV)
Yesterday I began reading William Bridge's A Lifting Up of the Downcast. Though first published in 1649 this is a book that remains powerfully relevant to all Christians as it aims at leading the discouraged believer to recover gospel peace and joy. On the first page of the book Bridge explains the key to recovering such peace is through the discipline of preaching to ourselves. Working from Psalm 42:11 he says it this way.
In these words we read of the sad discouragements of a gracious spirit, with those remedies that are to be applied and used against them. The discouragements are expressed in two words, under two similitudes: "cast-down," "disquieted." As a man is bowed or cast down under the weight of some heavy burden, so art thou cast down, O my soul, says David: and as the sea in the time or a storm is much disquieted, so art thou also disquieted within me, O my soul. The remedies that he uses against these discouragements are two: self-reprehension and self-admonition. First, he chides himself for his diffidence and distrust of God: “Why art thou cast down, O my soul? and why art thou disquieted within me?” He chides and rebukes himself for it. Secondly, he admonishes and calls upon himself to wait upon and hope in God: “Hope thou in God.” Why? 1. Because I shall yet be delivered: “For I shall yet praise him.” 2. Because salvation belongs unto Him alone: “He is the health of my countenance,” or “the salvation of my countenance.” 3. Because He is in covenant with me, and I with Him; He is my God: “The health of my countenance, and my God.” - A Lifting Up for the Downcast, William Bridge (emphasis mine)
You cannot simply wait-out the darkness or discouragement. You must look again to the promises of God found in the word of God. You must stop listening to yourself and start preaching to yourself.
Though I am still working through the book, I heartily encourage you to read A Lifting Up for the Downcast, or The Bruised Reed by Richard Sibbes. These are great books that can help lead you from discouragement to joy. For more on the idea of preaching to yourself you can check out my little book, Note to Self: The Discipline of Preaching to Yourself.