Why is Sparta so powerful?

Could you elaborate on why Sparta was considered a formidable power during its heyday? Was it their military prowess, their strict societal structure, or perhaps a combination of both that gave them such an edge over other city-states? How did their unique training methods and ideology contribute to their dominance on the battlefield? Furthermore, what were some of the challenges Sparta faced in maintaining their power, and how did they overcome them? I'm intrigued to learn more about the intricacies that made Sparta such a formidable force in ancient Greece.