AI coach rewrites the rules of cardiovascular research

Every day, millions of Americans open a fitness app, glance at their step count, and may even feel a mild pang of guilt before closing it again. The problem with most health tracking technology is that it watches your activity, but it doesn't really know you. A research initiative out of Stanford University School of Medicine is betting that the difference between an app people ignore and one that actually changes behavior comes down to a simple idea: the right message, for the right person, at the right moment.