I remember, one day I was eating 찹쌀수제비 (glutinous rice dumpling soup), and I saw a man in the resturant. He said "Wow, this is really good for (our) health" while he was eating the same food. He looked like he truly believed this and was enjoying the food. Since then, I always make sure to say those exact words before I eat it like him and 찹쌀수제비 became my favourite food. I think it's a kinda of placebo effect. Things go as we believe.