The treatment you receive as a child shapes your behaviour towards your health as an adult
Your childhood experiences shape you, and therefore your beliefs. Those beliefs shape your behaviour and conscientiousness. Studies have shown that the more conscientious you are as a child, the better your health is across your lifespan. A study was undertaken where children aged close to 10 years of age were assessed by their teachers on their levels of conscientiousness. When these children were observed again as adults, at a mean age of 51, various health checks were conducted on them. It was found that children that were regarded to be more conscientious had better global health than those that were not. 
Levels of conscientiousness are not set in stone throughout life. They can be developed as you transition through life. There are factors associated with the idea of being conscientious. When people engage in tasks that they find fit with their values, find enjoyable and important, the level of conscientiousness towards the task improves. A growing number of studies suggest that personality traits that are problematic to health can be improved, and this includes conscientiousness. By taking a bottom-up approach, and targeting the core personality traits, over time an individual is capable of altering these to generate healthier, more conscientious behaviour.