While it’s nearly impossible to avoid the inevitable loss of physical function that accompanies aging, a study out of the Institute of Epidemiology and Health Care at University College London suggests that seniors who enjoy life enjoy improved mobility and live longer than their more sour peers.

While happiness itself does not enhance or preserve one’s physical capabilities, happier people do tend to be healthier and more active, which in turn is linked to increased mobility, even in old age. Though the reverse is also true (healthier people also tend to be happier), scientists say that’s not the explanation. The happiness factor is important, regardless of health.

“We have previously shown that positive well-being and enjoyment of life are predictors of longer life,” said study author Andrew Steptoe. “Older people who report greater enjoyment are less likely to die over the next five to eight years than those with lower enjoyment of life.”

The study tracked nearly 3,200 men and women aged 60 and up over the course of eight years and periodically surveyed them to assess their levels of happiness. Of those who reported getting the most out of life, only four percent reported developing problems with everyday physical activities. Among those with the lowest satisfaction levels, the instances of difficulties more than quadrupled, increasing to 17 percent. Those who were happier also demonstrated a slower decline in walking speed.

“These associations could be due to many things: the people with greater enjoyment of life could be more affluent, have less physical illness or disability to start with, or have healthier lifestyles at the outset, and these factors could predict the changes in physical function over time,” Steptoe said. “But what we found is that baseline health, economic circumstances and lifestyle explain only about half the association between enjoyment of life and deterioration in function. So there is more to it than that.”

The results reveal that while happiness and enjoyment of life clearly mean something, scientists have yet to establish anything beyond a correlation between happiness and health. Whether healthy people are just happy to have their health or happiness is a driver of that good health, it’s clear that waking up on the right side of the bed never hurt anyone.