I was there in that same place not long ago. I have learned the hard way that the enemy not only puts those gloom and doom thoughts into our mind, but its also some kind of wound/wounds that we need healing and deliverance from. Anything that is not good and perfect is not of God. Command those thoughts of depression to leave and and for the depression to break in the name of Jesus. We have power and authority in the name of Jesus to tell Satan to leave our thoughts alone in Jesus name.
I ask you God to heal this person's mind, will and emotions and to bring all thoughts that are not of you God, captive and for new thought patterns to take place and take over the mind.
Blessings and peace to you!
If there is healing you need concerning any kind of trauma that you went through that has not been addressed, I suggest finding a good Christian counselor to go talk with. There is no shame in doing that, I had done that myself for quite some time and it brought me great healing.