Many sources on the internet (example) repeat this list of findings purportedly from a Duke University study on what characteristics contribute to one's "peace of mind":
- The absence of suspicion and resentment. Nursing a grudge was a major factor in unhappiness.
- Not living in the past. An unwholesome preoccupation with old mistakes and failures leads to depression.
- Not wasting time and energy fighting conditions you cannot change. Cooperate with life, instead of trying to run away from it.
- Force yourself to stay involved with the living world. Resist the temptation to withdraw and become reclusive during periods of emotional stress.
- Refuse to indulge in self-pity when life hands you a raw deal. Accept the fact that nobody gets through life without some sorrow and misfortune.
- Cultivate the old-fashioned virtues—love, humor, compassion and loyalty
- Do not expect too much of yourself. When there is too wide a gap between self-expectation and your ability to meet the goals you have set, feelings of inadequacy are inevitable.
- Find something bigger than yourself to believe in. Self-centered egotistical people score lowest in any test for measuring happiness.
"Peace of Mind, Factors Contributing to Emotional and Emotional [sic] Stability," Duke University, 1980.
And that seems to be a dead end. Does this study exist? If so, where can it be found?