Wiki entry를 보니까 Mens sana in corpore sano (a healthy mind in a healthy body)는 오역보다는 인용부분이 원래 맥락에서 분리된 현상이 아닌가 싶습니다만.
Over time and separated from its context, the phrase has come to have a range of meanings. It can be construed to mean that only a healthy body can produce or sustain a healthy mind. Its most general usage is to express the concept of a healthy balance in one’s mode of life.