Acceptance

Rui appreciated the time that Senior Sarak took to explain all these matters to him. It was definitely quite insightful and did not leave him stumbling in the dark. 

"If the strength of Martial Heart is a variable, then does it grow stronger over time?" Rui asked.

"Of course, this happens with or without the activation of the Martial Heart." Senior Sarak explained. "The Martial Heart is an accumulation of hidden power slowly created by the body trickling energy into across the lifetime. That does not suddenly stop once you activate it."

"I see..." Rui murmured. 'That probably explains why my Martial Heart was weaker than Ieyasu's.'

In which case, older Martial Artists were probably significantly stronger than he was. Although he understood the reason behind this rule, it was still an unpleasant realization. He did not want to wait decades to reach that level of power purely because his body's natural growth could not keep up with him.