Just like stacking boxes, the higher you stack, the more difficult it becomes; it's not as simple as adding a year's strength for each year of cultivation!
Therefore, during this period, Su Changkong had been considering whether he could change the cultivation environment to promote the progress of the Turtle Breath Technique.
Just as martial artists who cultivate Fire Attribute Techniques progress faster in hot climates, and those who use Cultivating Cold Attribute Techniques see double the efficiency when training in cool, icy environments, the importance of one's surroundings is evident.
Having reached a plateau with his Turtle Breath Technique, Su Changkong wondered, could he perhaps train underwater? By harnessing the change in environment to apply new pressures on his body, he hoped to make his cultivation twice as efficient.