For decades, public health authorities have aimed at better policies to drive citizens toward healthier behavior: smoke less, exercise more, and eat more healthily. We have all heard these slogans on more than one occasion. But the success of all these efforts has been moderate, because, despite knowing better, people do not always and fully follow the advice given by public health authorities -- for various reasons, such as lack of funds, time, and willpower. The session will summarize recent research on the nature of human behavior, helping to gain a better understanding of where policy-makers should intervene to get people living more healthily.