Next time you consider ditching the gym in favour of a pizza and a film (for the fifth consecutive day) spare a thought for your mind.
Regular exercise - even light exercise such as going for a walk or gardening - may help prevent depression in later life.
Analysing the results of 26 years' worth of data, researchers found that 25 out of the 30 chosen studies mark a correlation between lack of exercise and depression in later life.
"I'm active so I wasn't surprised to find this, but 25 out of 30 showed a significant effect and that was unexpected," says George Mammen, Ph.D. candidate and co-author of the study.
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"If you're not physically active, you should start," Mammem tells NBC News. "We usually think of exercise in terms of weight and how we look, but it's also a way to maintain mental health far into the future."
The study was carried out at The University Of Toronto and published in American Journal of Preventive Medicine.