The physical body is the exclusive medium for mental and spiritual development, making physical health vital to character.

Original passage

The body is the only medium through which the mind and the soul are developed for the upbuilding of character. Hence it is that the adversary of souls directs his temptations to the enfeebling and degrading of the physical powers. His success here means the surrender to evil of the whole being. The tendencies of our physical nature, unless under the dominion of a higher power, will surely work ruin and death.