(NYTIMES) - Years ago, when I was in college, I visited the dorm room of a fellow student. On the wall above his desk, he had posted a handwritten sign. "Just do it," it read in blocky letters. Nike's slogan was intended to capture an attitude towards athletic endeavours, but this undergrad was applying it to mental exertions.

I pictured him sitting at his desk, working hour after hour on his German verb conjugations. At some point he would become restless, lose focus - then look up at his sign, set his jaw and turn back to his studies, determined to crush them like a 100m dash.