We’ve all heard the advice: Take 10,000 steps daily. That seemingly simple goal sold millions of fitness trackers, most of which put your step count front and center.

It’s also one reason many of these gadgets end up gathering dust. I have a hard time squeezing in thousands of steps between meetings and lunch over my keyboard. And for those who can do it, 10,000 hardly guarantees a Kardashian physique.

Now fitness gadgets are ditching step counting for heart-rate tracking—and much more personalized measures. Mio Global, familiar to serious athletes for its wrist pulse trackers, developed a fitness metric that interprets your specific heart patterns based on a large health study. To maintain optimal health, Mio claims, just do enough strenuous activities to keep your Personal Activity Intelligence score at 100. Easy as PAI.

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