1. Depression (Feelings of dejection, sadness, apathy, inertia, difficulty in gaining energy or excitement, fatigue, pessimism, hopelessness, fear, attitudes of worthlessness, hopelessness, loss of interest, inability to experience pleasure, a loss of self-esteem or potential) is experienced by everyone. N. Kline wrote in the Journal of the American Medical Association (190:732-40), "More suffering has resulted from depression than from any other single disease affecting mankind."
2. David wrote in Psalm 43 (quickview)  feelings of depression & discouragement, "Why are you in despair, O my soul? And why are you disturbed within me? Hope in God, for I shall again praise Him, The help of my countenance, and my God." David knew that by taking his focus away from his own troubles & shift them to the purposes of God He would soon praise God for His overcoming deliverance.
3. When Elijah fled to the wilderness to escape Jezebel he plunged into despondency. He wanted to die & very well could have except for the treatment sent to him from God. Elijah complained to God, I have been zealous for Lord God Almighty, yet the Israelites have rejected your covenant & broken down your altars & put your prophets to death with the sword. I am the only one left & now they are trying to kill me too." To which God replied, "Go out & stand on the mountain, but the Lord was not in the earthquake, wind or fire, but then came a gentle whisper. Go back the way you came… I reserved seven thousand in Israel whose knees have not bowed down t Baal." (I Kgs 19) Let's remember that God personally speaks to us quietly through our times of prayer & Bible study through His Spirit encouraging, directing, enabling, empowering, inspiring, instructing, chastening, maturing, & blessing us. Psalms 42:11 (quickview)  says, O my soul don't be discouraged. Expect God to act! For I know that I shall again have plenty of reason to praise Him for all that he will do. He is my help! He is my God!
4. Even Jesus experienced discouragement in the garden of Gethsemane in Matthew 26:37-42 (quickview)  where He said to His disciples, "My soul is overwhelmed with sorrow to the point of death. Stay here & keep watch with Me. Going a little farther he fell with his face to the ground & prayed, "My Father, if it is possible, may this cup be taken from me. Yet not as I will, but as you will." Jesus knew that trials, troubles, & temptations would come to test His faith, yet He never wavered with unbelief. He was fully persuaded that God's will would allow Him to triumph over any problem, person, or power!
5. Job experienced such awful troubles that he nearly despaired of life. His wife said, "Curse God & die" (Implying that then his human sufferings would end, as well as her own). Instead, Job refused to give into the mis-belief that bad things cannot happen to good people. He finally realized that his self-righteous attitudes were wrong. The Lord helped him grow in faith, love, maturity, wisdom, & influence through his trials. At the end of Job's life in Job 42:1 (quickview) ,2 He said, "Now Lord, I know you can do all things (Including taking me through difficult times for reasons that only you know) & that no purpose of Yours (Not necessarily the ones that I understand or agree with) can be thwarted.