The idea that physical exercise might do something really fundamental for our mental health is not immediately obvious.
But that is what the evidence implies... exercise is not only necessary for the maintenance of good mental health, but it can be used to treat even chronic mental illness. On the treatment side, exercise appears to be as good as existing pharmacological interventions across a range of conditions, such as mild to moderate depression, dementia, and anxiety, and even reduces cognitive issues in schizophrenia.
In summary, physical exercise keeps our brains healthy and encourages the growth of new brain cells ('neurogenesis') and the connections between them. Evidence is accumulating that many mental health conditions are associated with reduced neurogenesis in the hippocampus. The evidence is particularly strong for depression. Interestingly, many anti-depressants — that were once thought to work through their effects on the serotonin system — are now known to increase neurogenesis in the hippocampus.
Read the article here.