Wing Chun Kung Fu is often taught as a "hard" or "external" style. There are few schools that teach the internal method of Wing Chun.
When learnt the internal way, it is an extremely powerful martial art.
When people first start learning Wing Chun they learn how to block with their tan sau, or their bong sau. They are taught what technique to use in the right situation. Given a list of techniques, and training them continuously. This is learning the external way.
To focus internally on your Wing Chun, you need to study the forms in depth. You need to feel your body, and know every part of it. You need to learn how to relax, relax enough so you can feel how your joints move. This is the internal way, to discover your own body, how it moves and how it can generate destructive power.
You need to be able to feel your body, before you can connect it together to use as destructive force on others.
Wing Chun without any internal thought is a very weak martial art. Bong Sau is a very weak position. Chain punching is easily overcome, the hand positions are awkward. The punch is so close, that only big people can generate power.
If one study's their own body internally, they can find out how to relax and connect their body parts together. Imagine who can punch harder, a big strong man with a 10kilo arm, or a 40kg female who has discovered that with relaxing she can emit her whole body weight in her strike. To me, the more interesting of the two is the one who can connect her body weight.
With an external way of learning, or a hard style of martial art, to get more power one has to do physical training to gain strength and fitness. For someone learning a good internal style of Wing Chun, this is not the case. Although fitness is good for your well-being and health, it is not the way to learn internal martial arts. One must learn how to relax, release the tension in your body. Tension stops the connection from taking place and isolates your muscles into individual parts rather than connecting the body as one unit. Fitness training is recommended for well-being and health, but not necessarily to be good at an internal art.
For an Internal Wing Chun practitioner, doing the forms, and chi sau (the things that are unique to wing chun) is the way to get stronger. And this is not stronger in the physical sense, but you feel stronger to others.
I would challenge people reading this article to look up Chu Shong Tin on the internet. This man is now about 80 years old, and if you can see what he can do, you would agree that he is extremely powerful. For me, he encompasses what Wing Chun is all about. He is old, small (60kgs), but still can generate more force than anyone I have seen. This is rather similar to the story that Wing Chun was invented by a female. Wing Chun in its purest form has to be learnt as an internal style, otherwise it's origins and the kuen kuit (training tips that are handed down) do not make sense.
Once one can learn the internal power of the body, and use the mind to focus it's force, it has devastating potential.
Phillip Warburton
http://www.internalkungfu.com.au