With each passing day after quitting smoking you are moving away from life-threatening diseases like heart disease and stroke. The drop in the risk is sharp. As soon as you stop smoking within six hours the heart rate slows and the blood pressure becomes more stable.
It will take a day for the nicotine to get out of the bloodstream with which the level of carbon monoxide in the blood drops so that the oxygen smoothly moves towards the heart and muscles. One can feel the fingertips getting warmer and there is no more shaking of hands as they get steady. And for nicotine abstinence symptoms, there are even pharma medicines available, like Zyban, which relieve the body of all those symptoms.
Within a week of quitting smoking there is improvement in the sense of taste and smell and the protective antioxidants like Vitamin C increases in the blood levels. The coughing and wheezing will become less in 3 weeks time.
As the lungs natural cleaning system starts recovering it becomes easier for the system to remove mucus, tar and dust. You can add exercise to the regime to help the lungs do a better job. Zyban will meanwhile keep doing its own job of maintaining the decision of quitting smoking. The immune system has also begun to recover thus it is easier for the body to fight an infection. The blood becomes less thick, sticky and its flow all over the body improves.
It takes about a year for the lungs to become healthier which makes breathing easier. There is a large drop in the risk of getting a heart attack within 2-5 years and this risk continues to gradually decrease over time.
With increasing years the risk of cancer, lung disease, and such life threatening diseases lowers depending on the number of cigarettes one used to normally smoke and the time period they smoked for and whether one had a smoking-related disease before quitting.