Worried about my dads health?

basically he had a heart attack about 4 years ago because of smoking. afterwards, i think he gave up for about a few months, but the smoking slowly started to creep back in. he has tried to quite once more since then, and hasnt been able to. i dont think he smokes as much as he used to, but still..... i think now hes just given up giving up. he is very stubborn and thinks "sod it, i dont care if i die" and its just worrying me. he also gets stressed quite easily too, which is something else that contributes to a heart attack. he doesn't have an unhealthy diet, and probably could do with a bit more excersize. he also takes all of the pills that he is supposed to, the only real issue is smoking and stressed, because he smokes more when he's stressed. please dont tell me to talk to him about how i feel etc because my whole family have tried, and he just gets so worked up and ends up having an angina attack or something. is there anything else he can do which will help balance out the fact he smokes?? or at leats help?? and also, HOW CAN I STOP WORRYING. seriously, its ruining me. if i hear footsteps in the night i panic because i think its my dad downstairs having a heart attack. i just don't know what to do, someone please help!