The term "most overstrung" implies a state of being excessively tense or nervous. Some antonyms for this phrase could be "calm," "relaxed," "unworried," "undisturbed," or "composed." These words suggest a sense of peace and tranquility, or at least a lack of extreme stress or tension. Other antonyms might include "blithesome," "carefree," "nonchalant," "easygoing," or "nonplussed" - all of which convey a more carefree or casual attitude. Whether through conscious effort or fortunate circumstances, those who embody these antonyms can enjoy a more relaxed and peaceful state of mind than those who are most overstrung.