The antonyms for "putting up a fight" could include surrender, submission, yielding, or acquiescence. These words suggest a sense of complacency or giving up, rather than fighting back or resisting. Other antonyms could include retreating, fleeing, or running away, indicating a lack of willingness to engage in conflict or stand up for oneself. However, it is important to note that there are times when it may be necessary to surrender or retreat in order to avoid further harm or injury. Ultimately, the decision to fight or give in depends on the situation and individual circumstances.