I'm bipolar, so my depression can be epic.
When I am under stress, the depression (and all my other weird Aspire traits) escalate.
Exercise, something to do, etc., all help, but, when the depression gets bad, pushing oneself self to do those things is like trying to lift a car with one hand - might wanna, might tryta, but it's not gonna happen.
Meditation helps. Meds have helped, but the side effects are dismal.
Knowing, intellectually, that it is depression, that depression is a brain fault and the bleak outlook has very little to do with reality, that it is transient and will eventually end, helps.