Depression is a big one. It affects a lot of people in a lot of different ways. And sometimes it's hard to understand or put your finger on. There have been times in my life where I think to myself "my life is good, why am I not happy?"
I don't know truly what the answer is. But I do know that God never intends for us to suffer from depression. Not that we are sinners if we do, but it definitley reflects an area of life that may need closer looking at. God intends for us to have a life of love, joy and purpose. To have a life full of the fruits of the spirit. And the enemy does not. He does not want us to bear fruit, and his goal is to rob us of our God-given joy.
Depression is a hard one to fight because of it's very nature that makes us want to give up, crawl in bed, pull the covers over our head, and try to sleep away or hide from life. But life is a gift! And it's worth fighting for! I shudder sometimes to think of how close I came to giving up when I was younger. And how much I would have missed out on!
God did not give us life to leave us high and dry and without purpose wasting away in a pit of depression. That is never His intention for us! And if we are finding ourselves walking that path, and perhaps God seems very far away, my suggestion is to find a close friend you can trust and ask for prayer. And to keep seeking God and the hope and joy He promised us. And to claim His promise that He will never leave us or forsake us.