In this episode of the AG Training Podcast, guided by our article, "DEFINITIONS AND PRINCIPLES OF TRAINING – Part I", we discover how systematic training not only activates our muscles to improve performance through structural and functional adaptations but also integrates mental training as a crucial component for athletes and coaches. We address the three essential components for performance in competition: physical condition, mental preparation, and the influence of external factors, such as work-related stress and social context. We highlight the importance of managing competitive pressure and how mental preparation can make a difference in reaching an athlete's maximum potential. We dedicate a special section to the concept of supercompensation, explaining its four phases and how these biological adaptations can elevate physical performance beyond initial levels. Additionally, we discuss the importance of finding the perfect balance between hard work and rest to avoid burnout and maximize performance improvement. Finally, we challenge the common intuition about rest and performance with insights on how swimmers, accustomed to high volumes of work, often perform better with a certain degree of fatigue.