While it can't do anything to alleviate stress, a recent update to S Health will let you monitor your stress levels using nothing but your Samsung Galaxy S5. If you're feeling stressed, just place your fingertip on the heart-rate sensor and S Health will tell you roughly how stressed out you are (or aren't).
Before you start, head over to Samsung Apps and make sure that the S Health app is updated to the latest version. Once your update is done downloading (if necessary), you'll see a prompt to update Health Service, which is needed for S Health to run properly.
Now when you open S Health and tap on the menu in the top left, you'll see an option for Stress.
Place your finger on the heart-rate sensor on the back of your phone, sit still without making too much noise, and let the app measure your stress levels. After twenty seconds or so, your stress levels will appear in the form of a color-coded bar, with a small triangle indicating your results.
Samsung warns that these measurements should not be used for clinical or medical use, but if your stress levels are extremely high, you should seek professional help, or at the very least, take a breath, calm down, and try these 10 tips to reduce your stress levels.