Researchers found that anything from a stroll in the park to a run through woodland can have a positive effect on people suffering from depression and anxiety.
The study also showed that the positive effect on people’s mental health was 50 percent more than they might expect from going to the gym.
The researchers at Glasgow University looked at natural and non-natural environments for physical activity, including walking, running and cycling, and found that being around trees and grass lowered brain stress levels, the Telegraph reported.
The study, led by Prof Richard Mitchell, polled nearly 2000 physically active people in the 2008 Scottish Health Survey.
Only activities carried out in a natural environment outdoors were found to be associated with a lower risk of poor mental health.
Prof Mitchell said he was “surprised” by the scale of the results.
“There was around a 50 per cent improvement in people’s mental health if they were physically active in the natural environment, compared to those who weren’t,” he said.
“These aren''t serious mental health issues, more struggles in general life, things like mild depression, not being able to sleep, high stress levels or just feelings of not being able to cope.
“It seems that woodland and forest seem to have the biggest effect on helping to lower mental health problems.
“That makes sense with what we thought we knew. That is, the brain likes to be in the natural environment and it reacts to being there by turning down our stress response. Being in areas that have lots of trees and grassy areas help to calm us down, and obviously a forest has this.
“I wasn’t surprised by the findings that exercise in natural environments is good for your mental health, but I was surprised by just how much better it is for your mental health to exercise in a green place like a forest, than in other places like the gym.
“The message to doctors, planners and policy makers is that these places need protecting and promoting,” he added.
He said that taking a decision to exercise in a natural environment once a week could be enough to gain some benefit, and any additional use could have a bigger effect.