The phrase "took the bull by the horns" implies that someone takes bold and fearless action to confront a difficult situation. Some antonyms for this phrase might include hesitancy, timidity, or cowardice. Rather than facing the challenge head-on, someone who exhibits these traits may avoid it altogether or approach it with apprehension and fear. Alternatively, a person who chooses to handle a problem in a more cautious, deliberate manner might be described as prudent or sensible. Ultimately, the choice of words depends on the context and the speaker's interpretation of the situation at hand.