Different people will define internal in different ways according to their experience. Internal can be described depending on the context and the particular movements you’re engaging. In the context of this post’s topic, I describe it as focusing narrowly on more intricate, or deeper, levels of movement. This practice always leads to the most minute motion deep in your whole being, not just your body. The body is where you point your attention to in the beginning of your practice. But you also have your mind, your “spirit” or “shen,’ and your “Qi,” or energy.
By “internal” I am referring to “life force,” “energy,” Qi, which is what practitioners are trying to connect with. You’re not just learning moves and sets of moves. You’re learning how to feel the energy in any given moment. You’re learning how to be alive in the present moment!
Tai chi practice offers two basic areas of training: learning/memorizing a sequence of moves or form, and cultivating awareness of movement at deeper levels. The first helps to develop the external appearance of movement and the latter develops the internal. Single basic moves allow you to narrow your focus on both in interesting ways. Internal awareness takes more concentration. Not that it needs that much, just that we don’t typically ever focus on that, and require familiarity with it to utilize it more effectively.
At some point, a regular, sincere practice of focusing attention to deeper levels triggers changes in the quality of your movements. Your move may become bigger or more power may come with it. It’s exponential, as in what I’ve heard my teacher, George Xu, say often “minimum effort, maximum results.”
This idea defies what average people usually think. If your long-held thinking has grown static, shallow, and relies on unexamined assumptions you’ll have difficulty picking up on the more intrinsic details of taijiquan. Understanding this boils down to being free in your movement so that you will adjust to the constant flux of the energy of being alive. Let the qi move your body. Let the mind picture the move before you move at all. This might sound deep or even meaningless, but it fits with what I mean.
Dragon Journal of Taijiquan 