Who am I?

This patient has been bringing her sons to me for years. She really wants me to see her niece who is 18 "But, she says, she doesn't want to follow a diet, she hates taking herbs and she forgets to take her vitamins."

"Don't send her! i replied, who am I? Jesus?"

Really folks, that sums it up: i show people the way but they have to do the work. Unfortunately i can't just touch people and they get better. I wish! my lovable personality and sparkling sense of humour doesn't make me that good!"