Re: any ex smokers?
I smoked hard from the age of 13 all the way through to 24.....Cigarettes and green. And I suffer from asthma.
I started training at about 24 when someone asked me to run a 10k road race.
In 6 months I went from being able to run for 20 minutes until I reached complete exhaustion, to being able to run for an hour (At this stage it was still very hard to run for an hour).
The next from months 6 - 12 I went from running a 10k - to a full cross country marathon with a combination of football (soccer), 1 hour runs, boxing training, and weights 5 times a week.
I built it up slowly, and am now 30.... Running for an hour is verging on easy, and I am in the shape of my life and still train on a regular basis. I would say my lungs are fully recovered, and I feel great.
I honestly think if you train hard you are looking at about a year for a full recovery, but its also is going to depend on what you eat, as well as how you train.
I would recommend lots of road work to get your lungs working again. Like the above guy said I would recommend a combination of sprints, and long distance runs along with the boxing training.
But you need to keep it up, and start eating healthy say 80% of the time minimum.
Trust me though, you can get there. My boxing fitness is now really good considering where I came from.