Is it easier to motivate people to change by scaring them or by inspiring them? And is it more effective to marshal data points, or to craft a narrative? I'm at the Imagine Solutions conference in Naples, Florida, and change is on everyone's mind. But though we're ostensibly debating issues like health care, the environment, energy, and the economy, I keep picking up on the meta-debate about what kind of leadership these issues require. Dean Ornish, for instance, spoke Monday morning about the motivational power of focusing on the positive. He's a doctor who champions preventive medicine (he's the founder and president of the Preventive Medicine Research Institute). He lambasted what he called the false choices between what is "fun" and what is healthy, and instead called on medical leaders who focus on the benefits — the fun side effects, as it were — of living a healthier life. And to convince us, he presented intense quantitative data culled from his research: tumors arrested (and by how much), heart disease reversed (and how quickly), genes expressed and unexpressed (with color-coded diagrams.) (Yes, living healthier can actually turn harmful genes "off." But I digress.)