How to build a powerful and healthy pair of lungs? The most simple method is jogging. You only need a pair of good running shoes (aka Rockport, no commercial intended) and the perseverance to do so. This method is for the young and athletically inclined. Apart from athletes, there are other professionals who need to train up their pairs of powerful lungs, for example, professional singers and windwood instrumentalists. For them jogging helps too, and much so the training method of the internal arts, in particular those with meditation as an essential element.
When we say "to train our lungs", we are talking about training the power of our breathing muscles which are responsible for forcing air in and out - against atmospheric pressure. Since our lungs are housed inside our body, expansion and contraction of which will necessitate pushing some of our body parts outwards. In normal breathing at rest, we unconsciously choose the least resistance which comes from our ribcage being pushed slightly upward and outward. This is usually called shallow chest breathing. Power breathing on the other hand is traditionally called abdominal breathing, which involves both the abdomen and the chest. In the limiting case, it involves our whole body.
How to train for power breathing in the internal arts? Like any muscular training, we have to create resistance for the responsible muscles resulting in breathing that uses as much lung capacity as possible without creating shortness of breath. In other word, the requirement is to use maximum capacity to be done in a relaxed way. Seasoned meditators can be seen as very relaxed as are professional singers and windwood instrumentalists. Without adequate relaxation, the meditators, singers and instrumentalists can possibly breath to full capacity, but cannot possibility perform to a satisfactory standard in their respective art forms.
In creating resistance, a student has to mindfully connect his lung muscles (i.e. muscles responsible for breathing) to his body parts which in the first steps (101 and 102) involves our two major joints: his shoulder and pelvic joints. and in order that such connection can be meaningful, a student first has to open his shoulder joints and pelvic joints (and make them into "spring-like"). The latter for tai chi or chi kung systems is called slow movement exercise and for Indian yoga, it is called asana. With a trained supple body, a student is ready to learn the art of power breathing.
In chi kung systems there are always two parts: movement forms and stationery forms. In Yoga, there are asana and pranayama. All have to be done with a meditative mind, otherwise no effective connection will be possible. The concept of points-stretched-body-relaxed is also very important. It is never total relaxation, otherwise there will be no work being done. However, a student must know which points to stretch and how to stretch and what parts to relax. The details of which will go beyond this article. Suffice to say, without such (empirical) understanding there, again, will not have effective work being done.
A pair of powerful lungs is essential for students who aim for a deep understanding of the internal arts and to explore into the interesting subject of meditation. Without a pair of powerful lungs, our mind cannot effectively relax, not without much conscious mind control [for example "let me relax (be mindful) here, and then let me relax (be mindful) there"]. Last words: a student cannot effectively meditate when his conscious mind is needed to command him to relax. Or lightweight meditation never works.