There's an old adage that money doesn't buy happiness; but those of us who know what it's like to be short on cash have probably had our doubts about it.
I mean, sure, you can't literally go and buy yourself a shot of joy or elation, but you can buy a three-week cruise around the Bahamas, or a relaxing day at the spa, or a large stuffed crust pizza - and those are basically the same thing.
According to research from Yale and Oxford, however, there is something that can give you the same kick for free: exercise.
"Exercise is known to be associated with reduced risk of all-cause mortality, cardiovascular disease, stroke, and diabetes, but its association with mental health remains unclear," the researchers said in their hypothesis. "We aimed to examine the association between exercise and mental health burden in a large sample, and to better understand the influence of exercise type, frequency, duration, and intensity."
So, in order to find out more about the connection between exercise and mental health (and happiness), they analysed data from over a million individuals.
During the study, participants were asked: "How many times have you felt mentally unwell in the past 30 days, for example, due to stress, depression, or emotional problems?" Then, they were questioned on how much money they earned and how frequently they engaged in physical activities (and that included everything from mowing the lawn to looking after children to working out at the gym).
After collating the data, scientists discovered that people who regularly exercised felt bad for about 35 days in a year. Meanwhile, those who were not active experienced low moods for an average 53 days a year.
What's more, when earnings were factored in, researchers found that physically active people were just as happy as non-active people who earned an average of $25,000 more every year. So, yes - money can make you happier to an extent, but that same happiness can be attained by regular physical activity.
However, more exercise does not always mean more happiness.
"In a large US sample, physical exercise was significantly and meaningfully associated with self-reported mental health burden in the past month," the study said.
"More exercise was not always better. Differences as a function of exercise were large relative to other demographic variables such as education and income. Specific types, durations, and frequencies of exercise might be more effective clinical targets than others for reducing mental health burden, and merit interventional study."
If you're looking to improve your mental health, then, exercise seems to be the way of going about it.
You could also try to earn more money, of course - but the physical effects of getting regular activity benefit more than just your mental health. Frequent exercise can also improve your overall wellbeing, and that - in turn - will probably keep you happier in the long run.