Since I do not suffer from clinical depression, I found this an interesting take on understanding it:
At first, I'd try to explain that it's not really negativity or sadness anymore, it's more just this detached, meaningless fog where you can't feel anything about anything — even the things you love, even fun things — and you're horribly bored and lonely, but since you've lost your ability to connect with any of the things that would normally make you feel less bored and lonely, you're stuck in the boring, lonely, meaningless void without anything to distract you from how boring, lonely, and meaningless it is.
(a couple years back) gotten to the point where I was completely overwhelmed with emotion and started to emotionally drop out, which she sort of alludes to in the beginning, but I didn't go that far down the hole. All I know is, if that's just the beginning (maybe it's not?) then there's a whole lot to depression that a pick-me-up can't fix. My sympathies for those who struggle with it.