expression
it's hard to discipline one's mind
Proverb contrasting external enemies with internal ones; the real challenge is mastering one's own desires and weaknesses.
「山中の賊を破るは易く心中の賊を破るは難し」という言葉がある。
There is a saying: 'Defeating the bandits in the mountains is easy; defeating the bandit in one's heart is hard.'
A classical proverb of uncertain origin, often attributed to Chinese philosophy, contrasting external and internal struggles.