In general, consider combining these terms to your topic if you come across a lot of results:

Mental Illness

Neuroses

Depression, Mental

Depression in Adolescence

Depression in Men

Depression in Women

Depression in Old Age

Anger

Temper

(or search “Anger Management” as key words)

Self-defeating behavior

Self-destructive behavior

Manic-depressive illness

Manic-depressive psychoses

Obsessive-compulsive disorder

Compulsive Behavior

Procrastination

Avoidance (Psychology)

Anxiety

Stress (Psychology)

Performance Anxiety

Addicts

(Or state a particular addiction such as “Internet Addiction.” For substances addiction, use “Substance Abuse”)

Optimism

(combine with “psychological aspects” if need to narrow down your search)

Healthy Habits

Habit

(Use Health and combine with Habit or a particular habit. Or use the keywords “Healthy Habits”)

Habit (then combine with “Compulsive Behavior” or “Obsessive compulsive”)