Gu Zheng didn't feel comfortable when the cold energy entered his body, but at least now he had completely controlled his natal true fire spirit, so he had enough heat to resist the cold, which would not cause the birth of his natal true water spirit. This process became extremely difficult, otherwise the pain he would have to bear this time would not be easier than when he gave birth to his true fire spirit.
However, as the process of creation continues, the feeling of pain gradually deepens.