Well. Let me try to reverse that example. For instance, you have a child with particular condition. She would not benefit from what normal people (yourself included) would benefit. Your efforts in that regard is what? Parenting, imho, and not by example. Then there are more situations, as kids need to learn certain stuff and be mature before they are ready to try certain experiences. That's not leading by example, either. In fact that's leading by counter-example - as one man was saying "Do as I say, not as I do".