There are thousands of smartphone apps in Apple's App Store and the Google Play store to help you get fit or lose weight. One of the newest uses your heart rate to register stress, while another reminds you to "Stand up!" because being seated for long periods isn't good for you and could be "literally killing you." Some fitness apps are simple, more like games, but others can be complex -- mapping your walk, run or bike route with GPS and then charting your progress with vital stats. New smartwatches can present fitness data on your wrist while audible coaching can order you to "Speed up!" or "Slow down!" based on personal fitness goals. Here's a sampling of some popular fitness apps.