Congratulations on quitting smoking - this is the first step towards a healthier life. Your lung function will improve within days to weeks of stopping smoking. It will slowly get towards normal. Respiratory symptoms like cough, phlegm and wheezing will also decrease. Also, your excess risk of cancer will decline once you have quit smoking but remains slightly elevated due to a history of smoking. These are general numbers based on statistics but your individual risks will depend on a variety of factors. This would be a good time to get a full general health evaluation from your doctor and make healthy life style changes like increasing activity and exercise.You can improve your health by aiming for a better body mass index closer to 20 to 25.