These words look like "diversion", "un-fruitful", and "diverted".

Having fun is good. The Latin origin of the word, as seen in Spanish, makes it clear that "fun" is something "not productive"; it's "diverted" from the goal. Fun is something you do for enjoyment that is not part of your goals. Taken to the extreme, it becomes sloth. Taken in the perfect amount, it becomes refreshing.