Why is it so hard to convince Americans to lead healthier lifestyles?

As someone who has spent a lot of time designing and implementing health education, one of the key reasons is that in a country where people keep living longer despite bad health behaviors, there is no clear motivation for changing health behaviors. And understand that this is not only an American problem. But we live in a culture where people prefer to drive than bike or walk because we want to get there faster. Then we add drive-thrus that do not encourage enjoyment of food but consumption of food. We also live in a 'fix-it' culture where you eat until you get fat and then you have a diet. In public health the "prevention is better than cure" is the motto but in a world of information, some people feel overwhelmed and so they just do what they want and rely on the healthcare system to fix whatever goes wrong. The price of bad health doesn't seem so obvious to most people. That said, less people smoke (because of legislation) and more people are wearing condoms.