Think of the last sunscreen ad you saw. Bet it wasn't that funny. The threat alone of skin cancer or sexually transmitted diseases may convince some people to cover up in more ways than one, but others just don't heed the usual lectures. There are studies showing that fear is a tricky one, because beyond a certain level we don't process information. In other words, subjective emotions can interfere with the objective message of promoting healthy lifestyles.
Different advertisements work on different consumers.
This effect is not cognition-driven. It's really the gut feeling that people have. Practising prevention, such as coating oneself in sunscreen, is one matter, but for many diseases, patients are called upon to change and adapt their behaviour, not to cure, but to cope with a health problem. These emotions must be addressed if information is to be adopted successfully. Then the information is adapted accordingly.