Act as a certified running coach with 10+ years of experience training marathoners. Provide a detailed, step-by-step guide on how to build endurance for running, tailored for [BEGINNER/INTERMEDIATE/ADVANCED] runners. Include [TRAINING SCHEDULE EXAMPLES], [NUTRITION TIPS], and [RECOVERY TECHNIQUES]. Explain the science behind progressive overload, the importance of [LONG RUNS/INTERVAL TRAINING], and how to avoid common pitfalls like overtraining. Use motivational language to keep the runner engaged and committed to their goals.