There are three things that have always made my soul sing: nature, the undiscovered and cycling.
Nature:

Since childhood - and as one who spent their early formative years being raised in the country - nature has seduced and delighted me. In my youth, there was no greater delight, upon reaching a field, woodland or river, than to take off my shoes and socks and connect to the land; to feel it intimately and draw up whatever power, real or imagined, it might have. I would spend hours, simply staring at a tree, climbing and investigating it and its inhabitants: birds, insects, animals and the often overlooked, but ever present, lichen. Wildflowers and animals fascinated me, rivers and streams provided endless pleasure. Even inanimate objects, often overlooked, such as rocks, would, on close examination, be found to be "alive" in one way or another. And these things still provide the deepest of pleasure. Why, I could not tell you, although I know, I am far from alone; millions of people seem to share the same love and wonder of nature, at least to some degree.
Poets, artists and philosophers have vouched and prescribed a regular engagement with nature as the most effective of tonics for centuries. An early example is Aristotle who advocated walking outdoors to clear the mind. Or, let us look to Beethoven, who, writing to Therese Malfatti in the summer of 1808 - as he completed the 6th Symphony - revealed: