Let me tell you what happens when you stop smoking. Your body starts to heal itself, immediately. Thousands of tiny hairs in your lungs start to sweep out the tar and other junk that have accumulated in your lungs over the years. You will notice this after week or two. A productive cough will start to purge your lungs. This may continue for a few weeks. As the days turn into weeks and the weeks turn into months, your lungs heal and they become more efficient at clearing out the junk. After just two years of not smoking your lungs are 99% brand new. After five years of being smoke free your lungs are just like new.