Training is the process of working to improve. The specific type of training I'm referring to is the heavy-ass weights/movin' fast/buckets of sweat/crying from soreness/gallons of coffee/ personal relationship with your barbell type of training. But really, if your entire view of training begins and ends with actin and myosin, you are missing most of the point. Yes, we want to be bigger and faster and stronger.
But what we really want is to be better.
Better could mean many different things, but quality time with a barbell improves most of them directly or indirectly. Write 5 ways you could be better on a piece of paper, don't show me, seal it in an envelop, then give me an honest 6 months in my gym before you open it. I guarantee that you will be better in those 5 ways. Why does this happen? I don't really know. But I have seen it in myself and in countless others.
In some ways this seems unclear but its obvious really. We are forged in the fires of our self-made kilns. You make your habits and then your habits make you. The way you do anything is the way you do everything.
Training is a emotional/mental/spiritual journey as much as it is a physical journey.