If you're smoking a cigarette right now, I have good news for you: if you don't ever pick one up again, your body will go through amazing transformations within minutes of finishing your last one.
20 minutes after your last cigarette:
Your blood pressure and pulse will lower and return to normal. The temperature in your hands and feet increase.
After 12 hours:
The carbon monoxide level in your blood will lower and return to normal. Blood oxygen begins to increase. You'll feel more alert, sleep better, and be stronger.
After 24 hours:
Your risk of heart attack drops significantly.
After 48 hours:
Nerve endings begin to regrow and your sense of smell and taste will return.
After about 3 months:
Your circulation will improve, walking will be easier, and you'll cough less. Lung function will be markedly improved.
Between 1 and 9 months:
You'll have less sinus congestion, fatigue, and nearly no shortness of breath.
After 1 year:
Your risk of coronary heart disease is half of what it was when you smoked.
After 5-15 years:
Your risk of stroke returns to normal, as if you never smoked at all.
At the 10 year mark:
Your chance of developing smoking-related cancer is about the same as a non-smoker. Diet and smoking contribute to 60% of cancers.
After 15 years:
Your risk of coronary heart disease and heart attack is that of a non-smoker. Your risk of death has dropped to that of a non-smoker.