We must give a lot of thought to the future, because that is where we are going to spend the rest of our lives.

The future is not a foreign country we visit now and then; it is where we will live out our remaining days, so it deserves more than a passing glance. The joke hides a plain point: planning is not a gloomy chore but a way of taking seriously the person you are going to become. The attribution to Keynes is shaky, though. A very similar line is more often credited to the American inventor Charles Kettering, and no solid source clearly ties it to Keynes.

Still, it fits themes in Keynes's thinking. He argued that economic life runs on expectations about an uncertain future, that confidence and what he called animal spirits drive spending and investment, and that societies should not simply wait for things to right themselves. Looking ahead, in this view, is an active responsibility rather than idle speculation.

For a person today, it might mean setting aside an evening once a year to look honestly at your money, health and work. You could set up a small automatic monthly saving, book the checkup you keep postponing, or start a course that will matter in five years. Each is a small kindness to the self who will be living there.