Spiritual Depression: Its Causes and Its Cure, Dr. Martyn Lloyd-Jones, 1965. Gently but firmly addresses potential causes including inability to receive forgiveness for all sins, not moving beyond past failures, seeing only bad and not good, not recognizing false teaching, lack of faith, not seeing trials correctly, etc. This older book stays centered on Biblical solutions. Very helpful.
Baxter Directions for a Peaceful Death is an article of 15 points on a Christian approaching his death and what he should be thinking about. This theme is good for the sick, but everybody should also meditate on these things. (Baxter is reformed).
