My father use to smoke 30 cigarettes daily since from 20 years. He have consulted t doctor and checked his lungs, he do not have any problem with them and he do not have bp and
diabetes too. He have an intention to quit smoking for that since from yesterday he quited. He is feeling some headach and some minor kind of symptoms but still he controlling himself for not to smoke. Is it okay to quit smoking suddenly, if not please tell me in which way he should stop it.