Concentrate to breed happiness

“We see evidence for mind-wandering causing unhappiness, but no evidence for unhappiness causing mind-wandering,” Mr. Killingsworth says.

What psychologists call “flow” — immersing your mind fully in activity — has long been advocated by nonpsychologists. “Life is not long,” Samuel Johnson said, “and too much of it must not pass in idle deliberation how it shall be spent.” Henry Ford was more blunt: “Idleness warps the mind.” The iPhone results jibe nicely with one of the favorite sayings of William F. Buckley Jr.: “Industry is the enemy of melancholy.”