As it turns out, the thought that we need to take 10,000 steps — or walk around five miles — a day was an accident. It came from the need to market a product. I-Min Lee, MD, a professor of epidemiology at the Harvard T.H. Chan School of Public Health and researcher of physical activity, tells Refinery29 that in the 1960s, a Japanese company created a pedometer called “Manpo-kei” that translates to “10,000 steps meter.” “10,000 steps is a really catchy number,” she says. And so, it caught on. “It pretty much was in use without people questioning too much about it,” she says.