lungs aren't muscle so there's nothing specific you can do to train them like you might your legs but aerobic activity will get them back into what they do best which is process oxygen and send it to your heart. and after just a year of smoking you'll get it back. i suggest you just go slowly and work within your capability. keep in mind that it's not just the lungs you're fighting but deconditioning too. even if you hadn't been smoking you would still be struggling since it's been a year with no activity. don't expect to get right back into where you were fitness-wise when you stopped particularly if you were very fit but you'll notice effects in just a few weeks if you pace yourself and within a few months your fitness will improve substantially. so give it 12-16 weeks to notice real differences and then you can take it from there. good job on quitting smoking. it's the most dangerous health risk there is.
i recently quit smoking. how can i get back into exercising? any suggestions to help get my lungs back into shape?