Be happy!

Be happy, and you may hold the key to a longer, more active life.

A new study of older adults, published Jan. 20 in the Canadian Medical Association Journal, shows that people who said they enjoyed their lives were better able to keep up with daily physical activities and walked faster than those who weren't as satisfied.

"The study shows that older people who are happier and enjoy life more show slower declines in physical function as they age," Dr. Andrew Steptoe, a British Heart Foundation professor of psychology at the University College London, said in a press release. "They are less likely to develop impairments in activities of daily living such as dressing or getting in or out of bed, and their walking speed declines at a slower rate than those who enjoy life less."

The study looked at nearly 3,200 men and women over the aged 60 and older. They were broken up into three age groups -- 60 to 69; 70 to 79; 80 and up -- and were tracked for more than eight years.

The participants were asked to rate how fulfilled they felt with their lives using a four-point scale. Prompts included: "I enjoy the things that I do," "I enjoy being in the company of others," "On balance, I look back on my life with a sense of happiness" and "I feel full of energy these days."  

Researchers also conducted personal interviews to determine how much mobility the subjects had when completing routine tasks. They judged their walking speed using a gait test.

People who were the happiest were three times more likely not to have problems performing daily activities compared to those who were unhappiest. The people who were most joyful walked the fastest and were more likely to survive over the study period.

The youngest participants, those with higher socioeconomic status, those with higher education levels, those who were married and those who were employed had the highest happiness levels. People with chronic illnesses like heart disease, arthritis, stroke and depression were among the unhappiest people.

"Our results provide further evidence that enjoyment of life is relevant to the future disability and mobility of older people," Steptoe and the authors wrote. "Efforts to enhance well-being at older ages may have benefits to society and health care systems."

Happiness has been linked to other later-in-life benefits before. People who were happy in their adolescence were more likely to be wealthier adults in one study. Other research showed that happier people were 35 percent less likely to die an early death.