To start measuring your heart rate, boot up S Health 3.0 and tap to select the monitor.
See that sensor there, right next to the camera flash? That's where the heart rate monitor lives.
Press and hold your finger on the sensor; it'll glow red when it gets going.
You mustn't move or talk.
After several seconds, the S Health app spits out your heart rate. Samsung warns that its monitor isn't meant to replace sensitive medical equipment.
So what is the heart-rate monitor good for? Establishing a baseline, for one, so you can track your progress before and after exercise. The S Health app that houses the heart-rate monitor can also keep tabs on calories burned, your nutrition, and other exercise stats.