If you smoke, please stop.
The most important thing you can do to improve your health -- especially if you have COPD -- is to quit smoking.
Take your medicine.
Take the medicine every day as directed by your doctor, even if your breathing feels good. It is important to stop COPD exacerbations before they start. When you have chronic obstructive pulmonary disease, your lungs remodel and never go back to the way they were. By taking your medication, you will stop your immune system from overreacting to stimuli that can trigger aggravation. Spiriva (tiotropium) is a very good drug that has been shown to prevent long-term lung damage. Inhaled corticosteroids (mometasone or budesonide) are also very good. They have not been shown to improve survival, but they do improve quality of life.
It has been shown that activity will improve the health of your lungs and slow the progression of COPD. If you become sedentary, that can potentially lead to serious problems. A common downward spiral of COPD goes as follows:
Hyperinflation of lungs
Poor quality of life
Deconditioning and impairment of muscles
Severe shortness of breath
This chart is important because steps 1-3 get a little out of hand. Even if you take the medicine, your lungs are still damaged and you will still occasionally have COPD worsening. You can break this cycle by addressing inactivity. Remember, you don't have to run a marathon. Existing shortness of breath can limit how much activity you can do. Just do what you can. A little goes a long way.