According to the
Therefore, after telling the system to remind when five hours were up, he closed his eyes and willed some of the refined energy to appear in his first spirit vein. Once it appeared, he carefully started circulating it through his spirit veins.
Initially, he felt comfortable all over, but soon, the comfort morphed into discomfort and then excruciating pain. He was feeling as though he was being stabbed by thousands of sharp needles.
'Argh!'
He barely managed to stop himself from grunting out loud. At the same time, he frowned because when he was cultivating, he hadn't felt any pain. In fact, he had felt pleasure. At that time, he wasn't doing anything different, just the pathways of energy circulation were a little different.