The word "wimps out" is a slang term used to describe someone who lacks courage or resilience when faced with difficult situations. While there are no direct antonyms for this phrase, there are plenty of words that could convey the opposite meaning. For example, instead of being a wimp, one might be described as brave, strong, sturdy, or steadfast. Resilient, daring, and determined are also applicable antonyms. In short, anyone who displays courage, steadfastness, and endurance could be seen as the opposite of someone who "wimps out" when the going gets tough.