Antonyms for the phrase "gives it one all" include half-hearted, lackluster, lazy, apathetic, and indifferent. These words signify a lack of effort, enthusiasm or motivation in approaching a task or challenge, contrary to 'giving it one all', which means putting in all one's energy, emotion, and talent in accomplishing something. While there may be instances where a less vigorous response may be adequate, it is generally not advisable to exhibit such an attitude in crucial circumstances that may determine the success or failure of a project or goal. Hence, it is essential to develop a habit of being diligent, passionate, focused and persistent to attain desired outcomes.