I think harmless "rock-bottom rituals" can help. When I feel like everything I do is pointless so I have no motivation to do anything, spending a day just watching TV and eating junk food is like acknowledging to myself that I am sad and that it is okay to feel sad. It's normal.

I give the "sad" part of me its time, let it have its way with the unproductive day of TV, and then it's my turn again. Otherwise I will be constantly trying to fight it and that's exhausting. If I embrace it once in a while, most of the time it's not there.

Of course I'm talking about a day here. If it was more than a day, this kind of thinking would just be an excuse to spiral downwards.