“Self-discipline”
There are many important qualities that can contribute to a person’s achievements and happiness, but there is only one that begets sustainable, long-term success in all aspects of life: self discipline.
According to a study by Wilhelm Hoffman, people with high self control are happier than those without. The study discovered this is true because the self disciplined subjects were more capable of dealing with goal conflicts. These people spent less time debating whether to indulge in behaviors detrimental to their health, and were able to make positive decisions more easily. The self disciplined did not allow their choices to be dictated by impulses or feelings. Instead, they made informed, rational decisions on a daily basis without feeling overly stressed or upset.