Will my lung get better after I quite smoking?

I have smoked for years, but recently have cut it down to just a couiple smokes a week. However, during the last few years I really exagerated and smoked a lot. I feel like I'm often and easily out of breath and I wonder if i have done perminent damage to my lungs. So i'm wondering if my lungs will recoupe if I quite completely. If so, how long does it take...