What people don't understand about depression is how much it hurts. It's like your brain is convinced that it's dying and produces an acid that eats away at you from the inside, until all that's less is a scary hollowness. Your mind fills with dark thoughts; you become convinced that your friends secretly hate you, you're worthless, and then there's no hope. I never got so low as to consider ending it all, but I understand how that can happen to some people. Depression simply hurts too much.