Practice the fundamentals, from light to heavy, from slow to fast. When you first learn to punch, dont just start punching for several hundred repititions, making your hand like a cocoon; your strength must delivered outwardly. Southern Fist exhales Qi to urge Li (power), the result of success is just Qi. Northern Fist is particular to use the Qi to sink downward, it is more vital than Southern Fist, they (Northern Fist) create Li (power) from Qi, the result of success is Qili (Qi and Power)!
And then there is our Natural Style Kungfu, which uses intention to manipulate Qi, because Qi follows intention, the successful result is overbearing.
When you look at me not moving, I seem to have absolutely no strength. In three years I will be 90 years old, at 60 or 70 most martial artists can barely move but the hard kungfu persists. Qi goes down, but how does it come up (he pats his abdomen). You see my eyes wide open, eyes pierce like golden rays, just a turn of a hand and I can attack. Your kungfu, (he takes a students arm) come here (he says to a student). Watch, try and pull me, see what happens. As soon as you use strength I can disarm you. Look at the kungfu in my hands. My arms are just like lead pipes, I can break your arm with just a strike. If I want to hit you, you can't get away. This is what is called kungfu.
The word 'kungfu' means time put in. Actions must be natural, from light to heavy, from slow to fast, the punches need to reach, the kicks need to extend. The punches must reach, the elbow (he pats his elbow); the kicks must extend, the knee is like an axis when kicking. It is like there is a person in front of you, one person or 10,000 people it's the same, look between their brow, I want to come in I just come in, I want to go I just go, there is no one there, but it seems like there is someone in front, your fist comes toward (me) and then I strike, dodge smooth and sly evasion. You guys want to exercise, your just playing.
Translation by Joshua Shain and Wei Li of Wan Laisheng speaking to Xiamen students in video