A proper mind does not pollute the healthy body with toxic products (drugs / alcohol / ...). A proper mind does not throw the healthy body in danger to be burnt or heal.
Exceptions aside, healthy mind is a gateway to a healthy body. At a very basic level, people with mental health issues cannot keep a healthy life style. undetected mental health issues lead to self harm and harm to others, as 90 percent of mass shootings are attributed t mental and behavioral health issyes. Stephen Hawkins disability was not caused by his mind but his healthy mind became a reason for unprecedented contributions to science.
a healthy body can be a prerequisite for a healthy mind. however, not being physically healthy can motivate people to look for a peaceful mind; they want to compensate for their problem.