Most people, when they say they are doing nothing, actually mean "I'm watching a show I don't really care about," or "I'm painting my nails," or "Reading Reddit." When someone suffering from depression isn't doing anything, I tell you, we are not doing anything. I can literally sit for an hour, not moving, not watching anything, not talking, nothing. It is like I am too sad to even move. Even just standing up is beyond comprehension.
My grandmother suffered from depression and sometimes she would enter these catatonic-like states where she wouldn't move. She spent months at a time in the hospital. That was a long time ago, of course. There is no health insurance in the world who would pay for that shit nowadays. It makes me wonder, though, would I have been hospitalized fifty years ago?
Doing nothing isn't easy, either. I am too depressed to move, so I do nothing. Because I am doing nothing I feel like I am wasting time. Which makes me feel worse. Which makes me want to move even less. Which makes me feel worse. Etc. Usually, best-case scenario is that I fall asleep and wake up with a little more motivation. At least enough to get up. That is a start.
So, sometimes, when someone tells you they aren't doing anything they might be sitting in front of an open window getting soaked because they cannot get up to close it. Thankfully they still have the will to speak to you, so there is hope.