I'm not sure this is the type of depression being talked about here. It's unfortunate that we have conflated periods of being sad / down with clinical depression. I have no doubt that reading a book or cleaning the kitchen or accomplishing a goal can help with feeling down or general sadness, but clinical depression is a whole separate beast without such easy a fix.
Who said these were "easy" fixes, though? I am emphatically not claiming that "just doing something" will work. Though, fair that what I put there can seem that way.
I am more trying to claim that "just doing something" has an annoying track record of looking like "it" is what worked. I would fully believe that, in reality, the thing that worked was already at play before the success started happening. That is, fully depressed people don't succeed at any of these things.