Microsoft's initial Kinect sensor might not have been awesome for first-person shooters, but it rocked for fitness games. Redmond is taking this one step further for its next-gen console with Xbox Fitness, a subscription-based service for the Xbox One. Xbox Fitness promises "instant, personalized feedback" on heart rate and form (thanks to the new Kinect's innards), and celebrity trainers include Jillian Michaels and Tony Horton. It's bringing P90X and Insanity workouts, too. The service will be free until December 2014 -- with Xbox Live Gold, of course -- but after that, Microsoft could be locking it behind two paywalls, according to a leaked test-page spotted by NeoGAF's ever-vigilant community. We've reached out to the company for confirmation on pricing and will update this post if we hear back. In the meantime remember: Shut up, focus and do the work.