I have a job and no mental illness, although you'd probably never guess either one of those things given how much I post here

My husband was truly unable to work when he was in a MDE. However it was perpetuating -- from his account, he was depressed because he didn't have a job... but was too depressed to GET a job. Once he found the right antidepressants and had gone through enough therapy, he found a job and his recovery skyrocketed to the point where he is now -- fully functioning, albeit with some quirks, but nothing that depression management and more therapy can't deal with.

Good question, though. Until I experienced what he went through with depression (and consequently got to know you all), I never would have understood how someone CAN'T work due to depression. I would have been one of those "snap out of it" people. From the other side of the fence, it's really impossible to comprehend the depths that the disease drags you down to.