I smoked 2=3 packs a day for 40 years.
The coughing stopped within a week.
I go to respiratory therapy 3 times a week (emphysema, sarcadosis, COPD). My O2 sats used to average about 86. After 5 weeks they now are up to 90. My doctor has also taken me off two breathing medications already.
I will never be "normal" but the difference is amazing.