"If you can wait and not be tired of waiting." According to Rudyard Kipling, that was part of being a man. My sense is we need to strike a balance between productivity, entertainment, and thinking. I'm not ready to "raw dog" a flight (a new trend of staring straight ahead for an entire airplane flight), but I do consciously try to put down my phone sometimes when I am on the train or waiting for something to stay within my thoughts versus always trying to make sure I am entertained. My unscientific view is that our brain goes to mush if it constantly requires entertainment versus thinking for itself or gets worn out if it is always being productive.