The mural above is of the Shaolin Temple in China. It dates back to the Ming Dynasty, about 500 years ago. Some monks are doing external exercises and some are doing internal exercises. One of the main things in all Chinese external and internal arts is qi.
There are thousands of styles of “internal qi” training from all over the world of every culture on every continent. Most have a different perspective from Chinese culture. They have their own philosophy and wisdom, yet similar enough that masters from all traditions get “it”.
Chinese internal arts of nei gong are full of health, philosophy, martial arts, art/calligraphy and even spirituality all rolled into one practice. Over thousands of years of notes, folklore, wars, great teachers and masters the understanding only got better. These practices are only getting to be understood better with modern science of kinesiology, medicine, psychology and even physics. (Modern science unknowingly helped us understand qi much more than ever before. A consequence is that we are also distancing ourselves from qi.) Each practice has their specific goals, but together each practice helps the others.
Practice so you can feel qi flow through you. Quiet your mind, relax your mind, let go of tension, and deepen your breath. Practicing the flow is a lot of work, but anything worth anything needs a lot of work, and enjoyment.