a few weeks most of a year about 10 years never in a few weeks many of the effects on circulation improve. these can help some of the constriction feeling of the lung. in most of a year the asthma-like effects off small airway reactivity usually improve. If someone is coughing up considerable secretions daily then this is a chronic inflammatory state that may or may not be reversible. The wheeze itself is reversible and often mostly goes with not smoking, but that takes months. in about 10 yrs the increased cancer risk associated with cigarettes goes away; if you haven t got cancer by 10 yr after quitting, it isn t very likely to occur at all. Lung which is gone isn t coming back. much. there is in non-smokers about 20-30 cc of breathing volume lost per year. this is double in smokers and 4x higher in those who are coughing up considerable phlegm (COPD). There is about 20-30 cc of INCREASED breathing volume GAINED per year in those who quit (for 1-2 year, for a total of maybe 100 cc total). So... on quitting... first, being highly motivated. second nicotine replacement doubles your likelihood of success. Chantix does that, BUT also is NOT nicotine... it blocks nicotine. So, while with nicotine replacement you still are on nicotine if not cigarettes, with chantix you are not on either. Some anti-depressaants somewhat increase your likelihood of quitting. Third is realizing your trigggers. The things that trigger you to smoke. There are some rather innvoled ways of dealting with them.