Hanson Lenyoun is the head of health at Mark One. Data is hot right now. We generate tons of it, but most of it sits there, latent, unused and useless. This is particularly pronounced when it comes to health and fitness data, where we strap on our fitness trackers and expect the pounds to melt away with each step passively logged. But we haven't seen a dramatic improvement in our nation's health with the emergence of the "quantified self movement" and the pervasiveness of wearables. We still live in a country where two-thirds of us are overweight or obese and 80 percent of adults do not get the recommended amount of exercise.