When you quit smoking your lungs can and do begin to heal some.
However the longer you have smoked the more damage you have already done to your lungs and so your lungs may never fully heal.
For example if you've smoked for 40 years or more and then quit smoking then your lungs will heal some but not fully because you've already done a lot of damage to your lungs.
Still it's never too late to quit smoking because you do increase your chance of survival longer when you quit smoking no matter how long you've smoked.
However if you've only smoked for a few years or even 20 years and then quit smoking then your lungs will have more time to heal.
So you will be able to breathe better and live a longer healthier life once you quit smoking and you'll save a lot of money for other things as well.
The average smoker spends $10.00 to $20.00 per day on smoking which is $300.00 to $600.00 per month and sometimes more.
That's a lot of money to just burn up.