Exercise is not only good for you physically, it can help you emotionally, too. That is the finding of a long-term review of the role exercise plays in maintaining good mental health.

Researchers at the University of Toronto analyzed more than 26 years' worth of data, and found that physical activity - even as little as walking 20 minutes a day - can prevent episodes of depression in people of all ages.

While co-author George Mammen acknowledges that there are many factors influencing the risk of depression, he said there is a clear message from his study: If you're active, stay active; if not, get moving! He says the impact of being active "goes far beyond the physical."