how should can i help my smoking bf quite?

my boyfriend is 16 and he smokes. hes been smoking since he was 11 he says. right before the holidays i asked him to quite for me. he said he would by the end of the year. but then as the end of the year came closer he said he doesn't want to quite or be nagged about smoking. i really don't like it. and since then he has been smoking more and more. and also the more he smokes the meaner he seems to get. How can i get him to stop smoking?