The phrase "most debilitating" refers to something that hinders one's ability to function and perform daily tasks to a significant extent. Synonyms for this phrase could be "extremely disabling," "overwhelmingly incapacitating," or "severely limiting." Other possible synonyms include "crippling," "debilitating," "paralyzing," or "enervating." The intended meaning behind the phrase can also be conveyed through words such as "devastating," "disabling," "debilitating," and "limiting," each describing how something negatively affects one's vitality or ability to function. Ultimately, the choice of synonym will depend on the context and desired impact of the phrase.