What I am talking about when I talk about running

A runner mentioned a phrase his older brother, who is also a runner, taught him, and he has been thinking about it since he started running. This phrase says "Pain is inevitable but suffering is a choice." Let's say you are running and you tell yourself "This is painful, man, I can't go further," the part related to pain is an unavoidable reality, but whether you endure it or not depends on the runner himself. And this perfectly summarizes the important aspect of marathon running. It has been ten years since the idea of writing a book about running occurred to me, but the years passed while I tried in various ways, without actually settling to write it. Running is a mysterious subject, and I found it difficult to determine what I wanted to say about it. But at some moment, I decided to write honestly about my thoughts and feelings regarding running and to stick to my own style, and I found that this was the only way to move forward. I started writing gradually in the summer of 2005, and I finished it in the fall of 2006. Except for parts where I quoted from my previous writings, the main content of this book is a record of my thoughts and feelings without delay. I noticed that writing honestly about running and writing honestly about myself were almost the same thing. So I assume it is okay to read this as a kind of memoir centered on the act of running.