In 1965, a Japanese company called Yamasa Clock created a personal-fitness pedometer called the Manpo-kei, which means “10,000 steps meter.” The Japanese character for 10,000 looks almost like a person walking or running, which is likely how the gadget-maker landed on the name—and the number. It’s also an easy goal to remember, especially when accompanied by a sketch of a person who’s literally walking. But that benchmark wasn’t based on any scientific evidence.

There's no magic number of steps that can ensure your heart health.