“Once your brain has become accustomed to on-demand distraction, Nass discovered, it’s hard to shake the addiction even when you want to concentrate. To put this more concretely: If every moment of potential boredom in your life—say, having to wait five minutes in line or sit alone in a restaurant until a friend arrives—is relieved with a quick glance at your smartphone, then your brain has likely been rewired to a point where, like the “mental wrecks” in Nass’s research, it’s not ready for deep work—even if you regularly schedule time to practice this concentration.”