We all know the "aaaah" feeling that comes from being out in nature. But recently, a group of researchers quantified just how much "aaaah" benefit we get, as long as we're exercising at the same time.

We all know the "aaaah" feeling that comes from being out in nature. But recently, a group of researchers quantified just how much "aaaah" benefit we get, as long as we're exercising at the same time.

They found that just five minutes of walking in a pretty woodland setting, or gardening, or cycling around a lake — indeed, anything you do to get exercise while in a "natural" setting — could boost your mood and your mental health.

Their study in the American Chemical Society's semi-monthly journal, Environmental Science & Technology, found that "green exercise" promotes personal well-being, and five minutes is all the dose you need.

They analyzed 1,252 people of different ages, genders and mental health status drawn from 10 existing studies in the United Kingdom. All natural areas were beneficial, they found, but natural areas with water, such as a river, lake or beach, were even better.

"We know from the literature that short-term mental health improvements are protective of long-term health benefits," said researcher Jules Pretty, of the Interdisciplinary Centre for Environment and Society at the University of Essex in England. His colleague, Jo Barton, added, "so we believe that there would be a large potential benefit to individuals, society and to the costs of the health service if all groups of people were to self-medicate more with green exercise."