Children don't do what we tell them to do, they do what they see us doing. That's why it's so important that we as adults, parents, teachers, grandparents, etc. are good role models for our children.
A child needs a safe environment in which to grow up, develop and be themselves in order to reach their full potential. In a family where the parents have adopted a healthy lifestyle, the children also gets a better start in life.
The child follows its leader, just like any herd animal, and healthy parents are more likely to raise their children with a healthy lifestyle.