Best definition of mental health/mental illness?

[ketts726]

I have memorised my textbooks definition of each of them but I've seen others that are different and probably better to use so I was wondering which definition you guys will be using?
Thanks 

[monkeywantsabanana]

I'm using Grivas' although our school teaches from Oxford.

Mental Health: the capacity of an individual to interact with people and the environment in ways that promote subjective wellbeing as well as the effective use of cognitive, social and emotional abilities.
Mental Illness: describes a psychological dysfunction that usually involves the impaired ability to cope in daily life, distress and behaviours, thoughts and feelings that are atypical.

Examiners will accept a wide range of responses because of the different text books but from what I heard, the main definitions were taken out of Oxford.