Walking could be a useful tool in treating depression

Research in Scotland published in the journal Mental Health and Physical Activity has reported that walking had a "large effect" on depression.  The paper "Walking for depression or depressive symptoms: a systematic review and meta-analysis" is a report of an examination of the results of several studies on walking and depression and the aggregation of the results.

The pooled standardised mean difference (effect size) was -0.86 [-1.12, -0.61] showing that walking has a statistically significant, large effect on symptoms of depression.

http://www.sciencedirect.com/science/article/pii/S1755296612000099?v=s5

http://www.bbc.co.uk/news/health-17701485

There are still questions over how long, how fast and whether walking should take place indoors or outdoors. One of the questions that would need to be probed is whether the effect is from physical activity, or viewing natural environments, as proponents of the biophilia hypothisis would claim.   Either way, it would seem good practice in urban design to promote mental health by creating and managing urban environments where walking is pleasant, purposeful and natural.