From a psychic's perspective, depression is like a quicksand of unhealthy psychic energies. If you feel the ground slipping under your feet, you can take a step back, but if you're already stuck, the more you struggle the more you get drawn in.
At the core of depression are the feelings of helplessness and purposelessness. Depression often goes hand in hand with its cousin 'stress', which operates with feelings of confusion and indecisiveness.
The sticky psychic energies first envelope the consciousness of the depressed person, then slowly work to suffocate and increase the pressure. At this stage depressed people start exhibiting self-destructive behavior.
How to get out once you get stuck? It's pretty much a deadly trap and there is no easy way out. Learn to breathe - both on physical and psychic levels. Let the energies wash over you, let the pressure break you. When the sands of psychic energies grinded you down to your bare-bone essence - then you can recreate yourself anew with a strong backbone, a loving heart, and a clear vision.