The number one most important thing you can do to benefit your Lungs is to breathe. Most people breathe very shallowly, with little attention given to the process. Practicing proper breathing can have more health benefits than any other exercise you can perform. The following instructions are for abdominal breathing.
This exercise takes 5 minutes to perform. You should do it at least once per day, preferably in the morning before breakfast. If you have time, it can be done at night before bed also. This exercise causes the diaphragm to drop down, opening up the space in the chest. This allows more room for the heart and lungs to work. It increases oxygenation of the blood, acting to produce aerobic respiration and stimulate the metabolism. Moving the diaphragm massages the stomach, pancreas, liver, and large and small intestines. This increases peristalsis and improves elimination. In addition, the abdominal walls are stretched and exercised, providing increased flexibility and tone. Abdominal breathing also quiets the mind.
Sit comfortably on a chair in a quiet space. Your feet are flat on the floor, hands resting on your thighs, eyes closed and mouth closed with the tip of your tongue touching the roof of your mouth. Breathe gently in and out through your nose. Your breath should be slow, even, and not forced. Rather than breathing shallowly and having your chest expand, allow the breath to sink to the lower abdomen and expand your belly. When you breathe in your belly goes out, when you breathe out your belly goes in. The chest moves only slightly. With practice this motion becomes easy and comfortable. Practice for 5 minutes. Focus on your breathing, and try to allow any thoughts or distractions to just come and go.