You will feel the benefits of quitting straight away as your body repairs itself. Depending on the number of cigarettes you have smoked, typical benefits of stopping are :

• TWENTY-FOUR HOURS the level of carbon monoxide in your blood has dropped dramatically. You now have more oxygen in your bloodstream.
• DAYS your sense of taste and smell improves.
• A MONTH your blood pressure returns to its normal level and your immune system begins to show signs of recovery.
• TWO MONTHS your lungs will no longer be producing extra phlegm caused by smoking. Stopping smoking reduces the incidence and progression of lung disease including chronic bronchitis and emphysema.
• TWELVE MONTHS your increased risk of dying from heart disease is half that of a continuing smoker.
• TEN YEARS of stopping your risk of lung cancer is less than half that of a continuing smoker and continues to decline (provided the disease is not already present).
• FIFTEEN YEARS your risk of heart attack and stroke is almost the same as that of a person who has never smoked.

Source: www.quitnow.gov.au