He cites one study in which kids with attention deficit hyperactivity disorder (ADHD) were found to focus better on tasks when in natural settings instead of urban surroundings.

If you find yourself unable to concentrate, perhaps you will agree that not only children can fall victim to nature-deficit disorder. I would contend that part of the reason adults are increasingly stricken with anxiety, depression, and other forms of psychological distress is because they are simply not grounded.

I mean grounded here in the most literal sense: people are disconnected from the very Earth that sustains their lives. It is evident in the ways we produce our food, choose to work, and interact with one another. As we disconnect from nature, we also seem to disconnect from each other; our relationships sour and our mental health is compromised. And, as we continue to ignore the important role of the Earth in our lives, we allow the planet to slip ever closer to environmental ruin, and we unintentionally invite the physical illnesses that accompany this cancer, respiratory disorders, endocrine disruption, and so forth.