Alone in a crowd in Lost

How can one feel alone in a crowd? Surrounded by thousands and I feel as if I’m the only one there, lost in my head, filled with sadness. How powerful the mind is, and deceiving is the poisoned mind. I have more than most, yet I feel I have nothing and deserve nothing. Pain and sadness have become me, my food and water, I am drowning. No one understands, not even I.