You may have experienced the health benefits of a walk in the forest, or a stroll through the city park. But what are the mechanisms behind this? Well, we know from science that a diverse ecosystem supports a varied and beneficial microbial community living around and inside us. We also know exposure to green space, even within urban environments, increases our physical and mental well-being. Research has identified three major factors that can make us feel healthier—beneficial bacteria, plant-derived essential oils and negatively-charged ions. If you want to know the science behind the healing power of nature, this is a must-read.