In 2008, the U.S. Department of Health and Human Services released the first edition of the U.S. Physical Activity Guidelines, which recommended at least 150 minutes of moderate intensity or 75 minutes of vigorous intensity physical activity a week.

You probably know that walking 10,000 steps a day is the new “magic metric” for the health-conscious. Ten years ago if you asked someone how many steps a day they should walk, you’d get a shoulder shrug. Nobody counted steps.