That's very interesting but I believe paying people to not engage in something will result in abuse. Imagine all the people who will then say "Well, I'm talking up smoking so I can receive money for not smoking."

Paying people to engage in something like walking, where the financial costs will be lower than if they are not paid is not only smart economics but an assurance that individuals and the population will be far, far healthier. Also with walking many people will not engage as much in bad habits, like smoking or bad eating. And even if they do the they at least have some protection against the harms.