The phrase "most well-conditioned" refers to someone or something that is in the best physical shape possible. Some synonyms for this phrase could include "in peak physical condition," "extremely fit," "athletic," "toned," "ripped," or "muscular." Another option could be to use adjectives that describe the specific aspect of fitness that is being referred to, such as "strong," "endurant," "flexible," or "agile." Additionally, synonyms like "healthy," "wellness-oriented," or "health-conscious" could be used to refer to a person or lifestyle that prioritizes their physical well-being.