By any reasonable measure, one might think me depressed. I'm not leaving the house. The house is filthy. I have zero interest in seeing people. Chores are not getting done, including posting to this page. All I'm doing is surfing and watching TV, all day, every day. So why do I say I'm not depressed? Because I'm actually pretty happy with this state of affairs.
That would seem to be the line between depression and sloth.