I *highly* recommend the app called "Self-help Anxiety Management" or "SAM." This is a great free app for both Android and iPhone users for tracking, understanding, and overcoming anxiety. The easy-to-use program will help you examine the sources of your anxiety, and give you tips and exercises to overcome those anxieties. There are also discreet activities and games in-app that can pull you out of an anxiety attack during times when you can't find a quiet place to relax.

—Danielle Gonzalez, via Facebook

You may also want to check out these apps, which can all help you calm down.