No wonder Apple launched its watch/fitness tracker and is banking on its new iOS health apps—it's a multi-billion-dollar industry. But this NY Times article brings up a great point: If you have a life-threatening condition, don't use an app that hasn't been approved by your physician or the FDA. Oh yeah, and that fine print? Definitely read it before paying for an app. Something that's labeled 'entertainment' might not be what you want to rely on when it's something that you should probably see a medical professional about instead. What health or fitness apps do you use? Tell us in the comments!