liz---I was diagnosed with copd in april 2008. I have since spent hour upon hour researching the disease. The final outcome is really based upon how quickly the disease progresses. The better you take care of yourself the slower the disease will progress. Im in a COPD group filled with people who are approaching 80 years old and have had the disease for over 20 years. Being that your only mild to moderate I suspect you could have a long and healthy life.
The answers to your questions about what you can expect in the future and what will be your life expectancy depend in large measure on the actual pulmonary function numbers that led to the diagnosis of mild to moderate emphysema and the accuracy of that diagnosis pulmonary function vs. chest x-ray changes vs. the quantitative amount of emphysema seen either on x-ray or CT scan. This is also dependent upon the number of years you smoked, your current age and your family history; i.e. family history of emphysema or chronic obstructive pulmonary disease (COPD).
That you can exercise for 30 minutes on a treadmill, assuming a moderate speed and grade resulting in an elevation of your pulse rate above 130 or so, is a sign that you still have good pulmonary function reserve. That you quit smoking in time and will probably have reasonably good lung function for many years to come.
If you want a more accurate prediction, you should consult with a lung specialist also called a pulmonologist.
Just don’t ever smoke again.
Good luck.