Re: damage from smoking???
This is by no means meant to condone smoking, but just to put things in perspective. Smoking definitely causes lung damage, no doubt about that, but it does take a LOT of smoking to cause serious lung damage. Smoking is quantified in medicine by the number of packs of cigarettes you smoke a day (usually measured at peak someone ever smoked) multiplied by the number of years you've smoked. So a person who's smoked two packs a day for 10 years is said to have a 20 packyear history of smoking.
Generally, at a 10 packyear history (i.e. 2 packs a day for 5 years, or 1 pack a day for 10 years or half a pack a day for 20 years) one starts to see evidence of smoking damage to the blood vessels and the heart. People who have SMOKING RELATED lung cancer, generally have a smoking history somewhere around 40 packyears.
Because younger people tend not to smoke as heavily as a long-time 50 year old smoker, permanent lung damage is often not seen before the age of 30.
It's a GREAT idea you quit smoking, smoking DOES have deleterious health effects to much more than your lungs, but given that you probably weren't smoking full packages of cigarettes for years at a time, the damage you did to your lungs is fairly minimal and will likely not affect you later in life. This is of course assuming you maintain cessation of smoking.