A diathesis is a predisposition towards the development of a particular mental illness. It could be a genetic defect or an anatomical abnormality (ex. a biochemical disorder that leads to mental illness). According to the diathesis-stress model, individuals develop mental illnesses in response to a combination of stressful circumstances and genetic predispositions.

According to the diathesis-stress model, mental disorders are the result of a predisposition to mental illness and a stressful life event. In this theory, genetic abnormalities do not automatically result in mood disorders (e.g. like depression). They will only result in mental illnesses when combined with a traumatic life event, (e.g. the loss of a parent or abuse).

Eustress describes a stress we have "enjoyed” (e.g. getting into college or starting a new job). The experience is taxing; however, these are enjoyable tasks that advance our development. Note the prefix “eu” that is from the Greek meaning good, well, true, or genuine. It is used in words such as euthymia (a pleasant mood state), euthanasia (literally, good death), and Eucharist.

Many researchers believe that individuals have characteristic means of coping, even across a variety of stressful situations. Some individuals rely on healthy habits like seeking social support, relaxation techniques, or religion, while others turn to unhealthy coping behaviors such as alcohol or other controlled substances. A high level of perceived control over one's life can help individuals deal with difficult events.

First proposed by John Dollard and Neal E. Miller in 1939, the frustration-aggression hypothesis posits that frustration is the formation of aggression as a result of environmental circumstances frustrating our ability to complete perceived goals. Despite seventy years of research, the theory has little academic support, but it has served as the foundation for other, more successful theories.

Under both the original frustration-aggression hypothesis and modern interpretations of it, the frustrating circumstance immediately triggers the aggressive feeling in the individual. The act of aggression, if any, may not occur until later, but if a condition does not immediately produce at least some aggressive response, then it is not likely to at a later time.

Most modern theories of stress and coping psychology agree that across different factors (e.g. gender, race, trauma type, age, physical health and even personality inventory scores) one characteristic stands out because it possesses a strong correlation with successful coping strategies: a strong external support network.

The approach-avoidance model of conflict describes a situation in which a single goal or choice both appeals to and repulses the same person. Charelle's desire to have a child before menopause occurs is warring with her desire to remain in charge of her own free time. 

Approach-approach conflicts tend to result in an unstable equilibrium. This type of conflict arises when a person has to choose between two desires with positive outcomes. They create unstable equilibriums because as soon as a person moves towards one goal, they move away from another. These choices may cause them regret or dissonance in the future because one "cannot have their cake and eat it too." In other words, when someone is presented with two potentially positive outcomes, they may wish they had chosen differently depending on future circumstances. 

In an avoidance-avoidance conflict, a person must choose between two equally unpleasant alternatives. As they move toward one of the two options, the repulsion of the choice grows stronger, which pushes them back to a state of indecisiveness between the two unpleasant alternatives. This can be overcome through willpower. Otherwise, the individual will be propelled into a perpetual state of indecisive neutrality.