Chapter 80: Zyra's Outburst and Arthur's Conclusion.
Arthur knew that to recover his mana, he just waited for it to recover naturally and didn't do anything other than that. Even without learning new insights, he should have thought about this, but it was never too late.
He would stop using his mana around 5-6 points left in his stats, and then it would take about 4 minutes for it to recover fully.
He knew he couldn't control the mana outside in the atmosphere; however, that didn't mean he couldn't guide the mana that was naturally entering his body.
'I can feel the mana entering through the pores of my skin.'