I think when as unproductive come to my side I just enjoy the moment
There were only few times when the unproductive day comes to me so I just take my time, have a good sleep, eat foods that I want and call it a day.
This also will help me for the upcoming day where I surely will became more productive than my usual day.
I can say that after an unproductive day, I usually make the following day 2 times more productive.
I think it's my mindset that wants to cope up with the unproductive day