Greg McKeown, from his book, Essentialism:

If you believe being overly busy and overextended is evidence of productivity, then you probably believe that creating space to explore, think, and reflect should be kept to a minimum. Yet these very activities are the antidote to the nonessential busyness that infects so many of us. Rather than trivial diversions, they are critical to distinguishing what is actually a trivial diversion from what is truly essential.