The phrase "broke train of thought" refers to when someone loses their concentration or focus on a particular topic or idea. To express the opposite, we can use words and phrases such as "continuity," "coherent stream of thought," "uninterrupted flow of ideas," or "seamless progression of thought." These antonyms indicate a state of mental clarity, where the individual's ideas are well-organized and connected, and they can articulate their thoughts with precision and coherence. Maintaining a clear and focused train of thought requires concentration and practice, but it can lead to better communication, problem-solving, and decision-making abilities.