Taiji represents Chaos, and Chaos evolves into Yin and Yang.
Yin and Yang are opposing yet unified forces, an innate attribute possessed by all living beings. Nezha, with the assistance of Yin Yang Qi, found cultivation relatively effortless. As for the Fire Element, it's even easier—Nezha was already well-acquainted with the finest flames of the Primordial era.
As for Metal, Wood, Water, and Earth, Nezha would need to train gradually. With each additional color added to the Seven-colored Divine Light, the difficulty exponentially increased. Truly, it lived up to the reputation of a Great Divine Power.
After emerging from his retreat, Nezha bid farewell to Lishan Old Mother. He didn't return to the battles between the Shang and Zhou armies to watch the drama unfold. With combat growing increasingly gruesome, and daily scenes of death and severed limbs flying everywhere, there was no longer much to see.