Excellent work on stopping smoking.
Thats your first step to loving your lungs.
The after effects of smoking will show for the next few years. Smoking for 8 years or so and then expecting your body and lungs to jump back immediately to good health is unfair to your body.
Keep working out, start slow , gradually increase the intensity.
Do yoga breathing exercises to improve ling capacity.
You can buy a spirometer to practice and exercise your lungs.
Take
vitamin supplements.
It should slowly improve over the next 5 years.
Kindly consult for supplement prescription and further queries.
You are doing well. Continue with determination.