There will be Xbox Fitness being released at the end of this year so that you can get working on that New Year's resolution. It will be free to Xbox Gold members for a year. I'm pretty excited about it. It has some big names behind it and it will use Kinect to measure heart rate, balance, muscles, etc.
http://news.xbox.com/2013/09/xbox-one-xbox-fitness-unveiled
http://news.xbox.com/2013/09/xbox-one-xbox-fitness-unveiled