What Causes Shortness Of Breath When Suffering From COPD?

To Dr. Mintz: Ihave chronic copd but still have the capacity to do most activities without breathing problems. Doing heavier activities does cause shortness of breath but recovery is farly quick. In addition, I produce quite a bit of mucous that I think I clear out quite well. My question is how much longer do you think I have before my breathing becomes more difficult? I am a smoker and I understand all the risks involved but I enjoy smoking and I am hopelessly addicted. I really do not intend to quit since it is such a good pacifier that I don t want to let it go. As alcoholics consider alcohol as their best friend I somewhat feel the same about smoking. I m 70yo and my guess is that I probably have 2-5 years left. Do you agree? What newer ways are available to perhaps live longer? I am quite active but as I mentioned earlier I am hopelessly addicted and with all extending circumstances it would seem that my symptoms should be escalating but for the past several years CT-Scans and x-rays come back with the same results,moderate COPD. Are these Drs. missing something that I m not aware of?