Took a header is a phrase commonly used to refer to falling or plummeting forward, and is often associated with accidents or mishaps. Antonyms for took a header would, therefore, be words or phrases that describe the opposite or a different action. Instead of falling forward, a person could take a graceful leap or hop, indicating a controlled and deliberate motion. Alternatively, a person could remain stable and upright, indicating a lack of movement at all. Choosing the right antonym for took a header would depend on the context and the desired effect, and could range from playful to solemn.