What is a mental hygiene issue?

A practice. Here's a reference on the history of the term, "mental hygiene": http://www. Jhsph. Edu/departments/mental-health/about/origins. Html mental hygiene is the set of practices conducive to the preservation of mental health. Those practices have changed over the years, but taking care of physical health, meditation, socializing, taking time for gratitude, etc. Might all be mental hygiene practices.