Health coaching is an approach to helps patients in gaining the knowledge, skills, tools and confidence in becoming active participants in their own care. It does not only reinforce the doctor's caring plans to promote checkups, but also it incorporates health goals that patients set for themselves too.
You should not sell unprescribed medication to people is illegal because they could be considered drugs. It is unsafe because they do not need it, or if they did they could have their doctor prescribe it to them and they you would not need to sell it to them.