Lifehacker headline:
Study Confirms All Suspicions: Fitness Trackers Aren’t Magic Bullets
They quote The Journal of the American Medical Association:

Although wearable devices have the potential to facilitate health behavior change, this change might not be driven by these devices alone. Instead, the successful use and potential health benefits related to these devices depend more on the design of the engagement strategies than on the features of their technology. Ultimately, it is the engagement strategies–the combinations of individual encouragement, social competition and collaboration, and effective feedback loops–that connect with human behavior.
No fucking shit?
Let me get this straight: little electronic wristbands can’t magically get you in shape?
Next thing you’re going to tell me is Siri isn’t a real person.
Or that I have to make a concerted effort to achieve important things in my life.