When Mo Hua truly started learning, he realized that the Water Passing Step wasn't as difficult as he had initially thought.
The difficulty of the Water Passing Step lay in controlling spiritual power with one's Divine Sense to lead the physical body. The stronger the control of the Divine Sense over spiritual power, the more agile the movement of the physical body.
The Heaven Yan Jue, an ancient cultivation technique, according to Mr. Zhuang, doesn't boost spiritual power or strengthen the Five Elements but specializes in enhancing control over Divine Sense.
And Mo Hua was already a Formation Master who drew formations daily, making his use of Divine Sense stronger than that of the average cultivator. After practicing Heaven Yan Jue, it was like adding wings to a tiger, controlling spiritual power and driving the movement technique wasn't a difficult task at all.