I'm very realistic. Given time the lungs will usually repair themselves. Unless you are unfortunate enough to already be pre-cancerous or have early COPD.

"[h=3]Benefits of Quitting Smoking for Older Adults[/h]

• Quitting smoking has proven health benefits, even at a late age. When an older person quits smoking, circulation improves immediately, and the lungs begin to repair damage. In one year, the added risk of heart disease is cut almost in half, and risk of stroke, lung disease, and cancer diminish."
  http://www.lung.org/stop-smoking/abo...er-adults.html