Maybe you've never had depression, and you don't know what it's like. Here's a small glimpse:
It feels like everyone is happy but you.
It feels like everything is impossible and you don't want to try, because it's probably pointless anyway.
Being around other people feels like the biggest chore in the world. They're loud. They have "more important" problems than you do. You don't know what to say because you feel miserable and empty inside, but don't want them to pity you.
You're afraid people will judge you. You're afraid that they'll write you off as lazy, as imagining your illness as "all in your head", or that you're not a real Christian. Real Christians have faith and pray and get over sad feelings, right?
You feel guilty all the time. You feel guilty that you don't enjoy going to Church, even though you have a testimony and love God and care about other people. You feel guilty for not taking care of other people. You feel guilty for skipping class and making things difficult for your teachers and classmates. You feel guilty for being a burden for the people you love, even though they insist that you're not a burden.
You feel exhausted with all these strange emotions that don't seem to make sense, and you're ashamed that your emotions, not your logical reasoning, rules you 97% of the time.
Worst of all: it feels like it will never, ever end.
Disclaimer: Please don't be alarmed about the state of my mind. I really am working on this whole depression thing. I'm figuring out which antidepressants will work for me and I'm seeing a counselor. I just want to show people what it's like to be depressed. It's hell.