Are you having fun?
I watched a Feynman video where he highlighted "The Importance of Playing". He spoke of running into some problems with calculations and eventually he found himself sitting a cafeteria hardly feeling like himself. During his meal, someone threw some sort of frisbee or a lid or something, which piqued his curiosity, and he immediately began trying to work out the math and physics of what was taking place. After a while, he realized that he was having a tremendous amount of fun, and shortly thereafter it altered the course of his work - in a good way.
For as long as I can recall, I have been repeating; "If it's not fun, then why are you doing it?". Play vs. Depression is a lot like the article that I was about to attempt. They didn't do what I would have done, but they captured a Richard Feynman bit. They didn't highlight the quote I was looking for, but maybe we'll just leave this here and call it good.