If living in a big city has you feeling a bit down, there's good news: A brief walk in nature could be all it takes to chase away those negative thoughts.

At least that's the finding of a new study published last month.

In the study, a group of 38 Northern Californians (18 women and 20 men) were split up into two groups — one who took a 90-minute walk in nature and another that did the same walk in the city. The nature walkers reported having fewer negative thoughts about themselves after the walk than before the walk, while the urban walkers reported no change.

What's more, fMRI brain scans revealed less activity in the subgenual prefrontal cortex (sgPFC), a brain region that may play a key role in some mood disorders and has been linked with patterns of negative thought, according to the study. Those who went on the urban walk did not show any of these benefits, the study found.