Sometimes we feel unproductive, exhausted, don't make progress. This usually is the case if we don't work on the task that has the highest priority for ourselves. And our subconscious notices this.
In this case, it is sometimes best to just stop doing anything, and take a walk, or meditate. Or clean the apartment, make the laundry etc.
Don't use this feeling of unproductivity to watch youtube videos, go to an image board, watch a movie or use other kinds of social media! You will regret it. You feel just more unproductive and more exhausted after that.