Research shows interesting, new correlations between exercise and health. Even obese people who exercise are healthier than thin people who don't. A leading researcher on obesity says you don't have to lose weight to be healthy you just have to walk. People who exercise - no matter what their weight - have half the death rate of those who just sit around. Cara Hetland has the next installment in our Mainstreet Radio series, "The Fight Against Fat." She reports, increasing your life span could be as simple as walking 30 minutes each day.