It’s been a few months since many of us made New Year’s resolutions. Have you stuck with yours? Harvard Business School professor Leslie John studies how to help people change bad habits (and reinforce good ones) by looking at what makes them tick. Here, she discusses stickK, an application that motivates people by forcing them to put skin in the game of self-improvement. John is the author of the case entitled, “Making stickK Stick: The Business of Behavioral Economics.”