Why do I do it? I want to improve. I know I am building and maintaining a foundation for endurance, but I want my training to be comprehensive; I want to be a complete boxer. I've gotten wiser in my training. In earlier days, I'd be at the gym 5 or 6 days in a row, in the middle of sweat-drenched August, doing intensive workouts and sparring on at least 4 of those days. While I could often see my speed improving, notice my punches having greater power, and my defense protecting me more effortlessly from my opponent's blows, I frequently sensed that I was putting out a lot more than I was taking in.
I could call it over-training, and perhaps on some level it was, but that explanation was too facile for my taste. Others over-trained. I engaged in some more exotic behavior that defied labeling. No, "over-training" could not explain what I was doing. I was somehow immersing myself in an angst worthy of Kierkegaard, using that angst as a platform for my practice and development as man, as free agent in the universe, and as boxer.
For now, I continue to work on improvement each day. There's some Zen dying to leap out of the shadows and illuminate the nature of improvement itself, but it will have to wait.