Dr Samuel Harvey, lead author for the largest survey of its kind for any link between exercise and depression, said, “We’ve known for some time that exercise has a role to play in treating symptoms of depression, but this is the first time we have been able to quantify the preventative potential of physical activity in terms of reducing future levels of depression. These findings are exciting because they show that even relatively small amounts of exercise, from a minimum of one hour per week, has the potential to deliver significant protection against depression. Dr. Harvey found it fascinating that the first hour of exercise turned out to be crucial. Most of the mental health benefits of exercise were realized within the first hour of exercise undertaken each week. The researchers concluded that just one hour of exercise a week reduced the chances of developing depression by a massive 44%.