A recent study has identified two molecules able to transform white adipose tissue ("bad fat", responsible for excess weight) in brown adipose tissue ("good fat", consuming energy), bringing new hope for the treatment of obesity and diabetes. But the authors' announcement (more humorous than scientific) declaring that the study is thefirst step toward a pill that can replace the treadmill is inappropriate. It underscores the importance of employing preventive methods such as physical activity, whose benefits on health are well documented and which represents the best medicine available. Different means and tools are described in this article in order to improve the amount and quality of physical activity prescription in primary care.