Mental health in adults can be defined as the capacity of the individual, the group, and the environment to interact with one another in ways that promote subjective well-being, the optimal development and use of mental abilities (cognitive, emotional, and behavioral), the achievement of individual and collective goals consistent with justice, and the attainment and preservation of conditions of fundamental fairness and equality. 

The two cognitive and emotional components are inner psychological expressions of mental ability, while the single behavioral component is an outward expression of mental ability.  

Mental health in children and adolescents can be defined as the attainment of scheduled developmental, cognitive, emotional, behavioral, and social, milestones - as well as the ability to develop secure attachments, satisfying social relationships, and effective coping skills.

Following are fourteen abilities or characteristics that further define mental health in a mature mind:

1.- Able to attain autonomy, to take full responsibility for own life, and to never lie to oneself.

2.- Able to exhibit enthusiasm, integrity, self-respect, self-esteem, and a positive self-image.

3.- Able to maintain control of emotional responses such as fear, anger, rage, love, hate, envy, resentment, bitterness, jealousy, guilt, and anxiety.

4.- Able to enter and maintain mature, respectful, positive, fulfilling, and lasting interpersonal relationships.

5.- Able to relate to and experience feelings of comfort, understanding, and empathy in dealing with others.

6.- Able to develop courage and confidence, and find happiness and humor in self and others.

7.- Able to experience positive self-regard and respect for others, even in diversity.

8.- Able to develop understanding and tolerance in terms of racial, philosophical, religious, and cultural acceptance.

9.- Able to forgive and effectively manage life´s setbacks and dissappointments with maturity and resilience.

10.- Able to meet life´s vicissitudes and exigencies and employ effective and rational coping skills in addressing problems.

11.- Able to align expectations with reality, to develop and apply intellectual independence, and to demonstrate self-determination.

12.- Able to influence the environment and display adjustability and adaptability when needed.

13.- Able to understand that adult life is a highly competitive merrit autocracy, where the merrit deserved and the merrit obtained exert absolute power over almost everything else.

14.- Able to show an abscence of four key factors – known as the four “D´s” - which generally serve to define mental abnormality: 1.- deviance (from the accepted norm); 2.- dangerousness (to self and others); 3.- distress (subjective ill-being); and 4.- dysfunction (grossly impaired personal and social functioning).