Walking in nature

I spent most of the weekend away from the laptop. I found a small forest quite close to my house - it has roughly a perimeter of 6km. The place is dense with trees and only a handful of people roaming. I have been living in this area for close to three years and had no idea this place existed. I went there on both days - Saturday and Sunday. From where does this feeling of wellbeing come when one is surrounded by nature? There are things that money can’t buy.