Maybe you’re someone with a genuine neurochemical imbalance, in which case antidepressants might be effective. Or perhaps you’re just genetically disposed to feeling like this? If you’re content with your life circumstances, and there’s nothing in your past particularly tormenting you, it could just be purely biological. I think there’s always a reason we feel the way we do. Unfortunately, although we can often effect them, we don’t get to choose our feelings. Otherwise no one would ever feel extreme pain.