Nobody studied the 10,000 steps: a pedometer sold them

1965: Yamasa Tokei, a clockmaker in Osaka, puts a pocket pedometer on the market and calls it manpo-kei, Japanese for ten-thousand-step meter. There was no clinical trial behind that figure. It was a brand name, launched on the enthusiasm of the previous year's Tokyo Olympics, when the whole country had taken up walking.

The number that does have a study behind it is lower. In 2019 the epidemiologist I-Min Lee used accelerometers to measure the real step counts of 16,741 women averaging 72 years old, then tracked their mortality. Risk fell clearly up to around 7,500 steps a day; beyond that the curve flattened. And the benefit started far earlier: 4,400 steps already made a difference against 2,700.

What to do with this tomorrow. Open your phone and look at last week's average step count, not today's. Add a thousand to that average and leave the number alone for a full month. Count the days you hit it, not the steps you are missing.

If your average is 3,000, set 4,000 and forget the ten thousand until next month.