1. Continuous heart rate monitoring: Pair the watch with the Nothing X app. In the app, go to My Devices > Health monitoring > 24/7 Heart rate monitoring. Make relevant settings. Put on the watch and it will start to automatically measure your heart rate. 2. Manually measure your heart rate: (1) Put on the watch, and remain still. Press the button to open the function list, and select Heart Rate. Tap to enter, and the watch will start to measure your current heart rate. (2) Put on the watch, and remain still. In the main interface, swipe left or right on the shortcut cards until you get to the Heart Rate interface, and the watch will start to measure your current heart rate.