Moose, I am just entering my depressed state. What I decipher from the low feeling I describe this way. Its not like sadness, its like my instinctive ability to fight has such a low chemical response that if my heart beat and breathing didn't happen automatically, I would just stop. My brain senses this, and interprets this as sadness so I think of sad things.
For me, trying to see depression this way helps me to not get caught up in sad thoughts and ride the storm out better.
I am glad that you are doing okay.

Happy New Year.