The Galaxy S5's heart rate sensor has mostly been handy for fitness gurus, but it's now helpful for the rest of us, too. Samsung has pushed out an update to S Health that uses the sensor to track stress levels; if your heart is racing after a bad day at work, you'll know. The app also tracks long-term trends, so it should be clear when you're overdue for a vacation. While S Health won't help you get rid of the annoying coworkers or personal dramas that cause stress, the app will at least make it clear that it's time to relax.