Image by Bruno Nascimento via Unsplash
The short answer is yes.
There was a recent study that combined the results of 15 other studies ('a meta-analysis') and showed that 2.5 hours of brisk walking per week was associated with 25% lower risk of depression, and at half that dose, risk was 18% lower compared with no activity. The reasons behind this drastic reduction in depression were found to be:
Biological: Those who are runners will know when I talk about the 'runners high'. In the short term, the release of 'happy hormones', the activation of the endocannabinoid system and decrease in inflammation all contribute to the positive effects of exercise on the mood. In the long term, It has been shown that the brain anatomy 'changes' with long-term exercise that leads to a longer lasting effect.
Psychosocial and behavioral: improved physical self-perceptions and body image, more social interactions, and the personal development of coping strategies are some of the reasons why people started feeling less depressed.
Role of the environment: For those who used green spaces to exercise, ie, outside were associated with lower risk of depression.
What was interesting in the study was that even physical activity levels below the minimum recommended target by public health recommendations, had benefits than not exercising. There was limited extra benefit beyond a certain level. They end with a very powerful statement: If less active adults had achieved the current physical activity recommendations, 11.5% of depression cases could have been prevented.
This should not come as a surprise to many people. But this was the first time I read some scientific basis around this with numbers that show that physical activity should be recommended as a first line of treatment for mild depression.
It certainly did work for me: I started running to get over my depression. Being a goal/challenge oriented person, I set goals (5K race, the 10K, then half marathons and then a marathon) and I could literally feel the fog lifting off slowly till one day, my depression was hardly there. One caveat to this is that it doesnt last forever. I still get into bouts of depression if I dont do any physical activity. But I could do significantly worse.
So, if you are not really feeling that great, go outside and get a short walk in. You never know.
Here is the link to the study, if you want to learn more.