you should look into CrossFit. It is by far the best workout i've ever done for my lungs. I swam competitively for many years, have worked with a trainer, run, biked, etc etc etc. and CrossFit has been more beneficial than any of those other activities ever were. It basically combines weights and cardio in short, varied, intense workouts. olympic style lifting is also a large component of the workouts. don't be intimidated...i knew nothing when i started doing it but the coaches at the gym teach you how to do everything properly so you don't hurt yourself! every move and workout can be modified to every fitness level. tonight i worked out next to a 65 year old woman and a hugely strong 25 year old guy. anyone can do this. so to give you an example the workout i did tonight was for the lifting part was finding your maximum weight for an overhead squat (youtube that to see what it looks like) and then after that we did as many rounds as possible in 8 minutes of: 4 handstand pushups (again, modified because I sure as heck can't do a handstand pushup!), 8 kettlebell swings, and 24 situps. so the 4/8/24 is considered 1 round. the point is you are going all out but its only for 8 minutes. then you're done. i cough up so much crap, it's amazing. I've run across very few other CFers that crossfit but there are some out there and we've all experienced a ton of benefits from it. to find a gym near you go to http://www.crossfit.com/cf-affiliates/
http://journal.crossfit.com/medicalinjuries/
the link right above here is for a bunch of articles about people with all kinds of medical issues that have found crossfit to be of benefit to their lives....definitely some really cool stories.
seriously yall. do it. it's the hardest thing i've ever done but also the best! and it's all done in a group setting so it's fun!