GET MORE FROM YOUR TRAINING WITH HEART RATE ZONES When you’re out for a jog, on a bike ride, or using the elliptical, how do you decide how hard you’re working? Do you go by feel—thinking “this is easy” or “this is pretty tough”? Or do you periodically glance at your smartwatch and notice what “zone” your heart rate is in? I used to think cardio was just about getting out there and moving. But I’ve started to see it a little differently. It’s really about how your heart responds to what you’re doing. That’s where heart rate zones come...