Timeline of quit smoking health benefits:

• After 20 minutes - Both your blood pressure and your pulse rate will have stabilised at a more natural level. As your circulation improves, the temperature in your hands and feet increases to a normal level as the arteries recover.
• After 8 hours - The carbon monoxide level in your blood drops as the amount of oxygen carried throughout the body increases. Smoking hinders both brain and muscle functions by reducing the amount of oxygen available to inadequate levels. The levels of carbon monoxide will now be reduced to a level about 50% of what they used to be when you smoked. Another benefit, probably more noticeable to people other than the ex-smoker themselves, is that “smoker’s breath” becomes less pronounced.
• After 24 hours - Not only is your body now functioning more efficiently, the chances of enjoying your improved health are also increased. Not smoking for a day is all it takes to reduce your statistical chances of suffering a heart attack and improve your chances of surviving one. It also takes about 24 hours for the last of the extra carbon monoxide from smoking to be eliminated from your body.
• After 48 hours - Your senses of taste and smell have become much keener compared to their previously dulled state. Excess mucus and toxic debris that has collected over time will begin to be cleared from the lungs. Although there will initially be an increase in the amount of mucus dislodged from the lungs, breathing will gradually become easier. Amazingly, those nerve endings that were damaged by the smoking habit will begin to regenerate once you quit.
• After 72 hours - Your bronchial tubes become more relaxed and less constricted, making it easier to breathe. The risk of thrombosis is reduced as the blood’s clotting agents return to normal.
• After 2 to 3 weeks - Your lung capacity will have increased by up to 30%. In combination with improved circulation, this means that you will find it easier to engage in physical exercise.
• After 1 to 9 months - You will experience less coughing, wheezing, sinus congestion and shortness of breath. The fatigue associated with these symptoms will decrease as your overall energy levels continue to rise. As the microscopic, hairlike cilia regrow, they increase the lung’s ability to purify the air by once again filtering out impurities and clearing mucus. This also reduces the chances of developing an infection, especially in the sinuses.
• After 1 year - The excess risk of coronary heart disease is now approximately half that of a smoker.
• After 2 years - The risk of a heart attack drops to a more normal level.
• After 5 years - The risk of developing cancer of the mouth, throat or oesophagus will now be half that of a smoker. Abstaining from smoking for between 5 to 15 years will mean that you have reduced your risk of having a stroke to the equivalent of a non-smoker.
• After 10 years - Your lung cancer death rate will now be equivalent to that of a non-smoker. The risk of developing other cancers, such as cancer of the kidneys, pancreas or bladder, is decreased. Healthy cells gradually replace pre-cancerous cells in the body.
• After 15 years - Your risk of developing coronary heart disease will be the same as that of a life-long non-smoker.

* The timeline may be different for different people, just as some people are naturally healthier to begin with, the fact remains that your body will be better off once you quit smoking.