expression
it's all in the mind; everything depends on your attitude
Proverbial expression meaning that one's mindset or perspective determines how a situation is experienced.
同じ仕事でも、気は持ちようで楽しくも苦しくもなる。
Even the same job can be enjoyable or painful depending on your mindset.
気は持ちようだから、前向きに考えよう。
It's all in the mind, so let's think positively.
Similar meaning; 気の持ちよう uses の instead of は, and is slightly more common in modern usage.
A set phrase combining 気 (mind/spirit), は (topic marker), and 持ちよう (way of holding/handling). The exact origin is uncertain, but it reflects a common Japanese cultural emphasis on mental attitude.