Running a marathon is as much a mental challenge as a physical one. The first few miles feel easy, almost deceptively so, and many runners make the mistake of going out too fast. By mile sixteen the body begins to protest, and by mile twenty the famous wall arrives - a point where glycogen stores run low and every step requires a conscious act of will. Experienced runners know to respect the distance, to run with patience and trust in their training. The crowds along the route help enormously, providing bursts of energy at critical moments when the mind starts to negotiate with itself about stopping. Crossing the finish line produces a feeling that is difficult to describe to someone who has never done it. It is not just relief or pride, but something deeper - a confirmation that the body and mind are capable of far more than they usually attempt. Many runners finish a marathon and immediately begin planning their next one.