What exactly is mental health?

Adaptive or not. There are many answers to this, but one way of answering this very broad question is the idea of how adaptive a person's behavior is (or isn't) to social situations, i.e., the context in which the behavior is exhibited. For instance, jumping up and down and yelling during, say, a Catholic mass might be considered maladaptive/ inappropriate, in that context. However, not at all at a sporting event.
Mental Health. I define mental health as the ability to handle the challenges of life with flexibility and stability. Positive mental health includes being able to take the perspective of others, to handle our impulses and emotions, and to move on from trauma in a healthy way. It also involves good positive relationships with others in our communities, developing good social support.

Related Questions

What exactly is a mental health check?

See below. Appearence, cooperative, eye contact, speech, language, sensorium, thought disorder, perceptual disorder, suicidal and homocidal ideation, mood and it affect. Read more...
Wellness screen. A mental health check is brief screening of emotional, social and occupational functioning that is often done as a part of a annual medical check-up. Mental health checks are a good way of identifying people who have undiagnosed but very treatable mental health concerns. Read more...