A healthy mental state and positive mood may provide individuals with the energy to live longer and maintain good physical well-being, according to researchers at the University of Illinois.

A team of scientists reviewed 160 studies that examined mood and longevity, and found that the trials overwhelmingly pointed to a correlation between happiness and a long life.

"Current health recommendations focus on four things: avoid obesity, eat right, don't smoke, and exercise. It may be time to add 'be happy and avoid chronic anger and depression' to the list," said lead researcher Ed Diener.

Study authors noted that a good mood on its own will not cure disease, but that an overall good quality of life accompanied by uplifting emotions may reduce stress in these individuals, contributing to a healthier body.

To achieve optimal health, Ilchi Lee believes that an individual must have a strong mind-body-spirit connection. When these three elements are aligned – either through meditation, physical exercise or brain exercises – an individual has the ability to gain fulfillment and lead a full and happy life.