The phrase "took lying down" implies passivity, resignation or a lack of assertiveness in the face of an adversity. The opposite of this phrase can have different antonyms, depending on the context. For example, if we twist the meaning a bit and look for antonyms that suggest standing up for oneself, we could think of "fought back", "resisted", "protested", "challenged", or "defended oneself". Alternatively, if we focus on the passive or submissive aspect of "took lying down", then the antonyms could be "stood up", "asserted oneself", "spoke up", "opposed", or "took action". Regardless of the antonym we choose, the phrase "took lying down" suggests a lack of agency that can be overcome by being proactive and assertive.