I'll not be held responsible for any injuries or suffering if anyone tries this techniques. It requires special guidance from a qualified instructor. I doubt you will find many instructors that know this technique as they are very old techniques and are only usually taught to special students with high potential, dedicated, respect teacher and self-respect, and patience.
Stand in front of a well or a big tail container of water. While in horse riding stance thrust your fists towards the surface of the water 100 times. Do this during early morning or after midnight. You will seem like you are achieving nothing for a long time. After 1 or 2 years your fists will cause the water to stir slightly. Lots more practice will cause the water to become agitated and noisy. More practice will make the water sound like waves. At least 6 to 8 years practice will pay off as the water will sound the rolling of waves and your punches will be devastating.