As mentioned in my previous post, the list of necessary items for running is short. The simplicity of that brevity is one of my favorite things about running. It takes a body and mind willing to do it, and that's about it.
I have dabbled in and enjoyed other sports. I grew up on a basketball court. I raced bikes, both road and mountain. I rock climb, raft, ski, and backpack. None of them mean to me what running does. And part of that is complication versus simplicity.
All those other sports require some sort of gear, or a ball, or a team. Gear can be cost-prohibitive, cumbersome, and potentially fail with varying degrees of calamity. Ball sports require a suspension of disbelief. It takes a group of people to agree that for whatever the duration of the game, the inflatable ball is the most important thing in the universe. When one stops to really consider that, it's borderline whimsical.
Running is cut and dried. It requires no gear, tools, mechanization, or rule books. It is historic. It is rooted in biological evolution. We can now leisurely do something that was once selected for by the environmental pressures placed upon our ancestors. Running was once the very thing that kept us alive. That's about as simple as it gets.