There are several synonyms for the phrase "grew tired", including "weary", "fatigued", "exhausted", "spent", "drained", "exerted", "weakened", and "flagged". Weary implies a gradual loss of strength or stamina over time, while fatigued suggests a weariness caused by physical or mental exertion. Exhausted conveys a complete depletion of energy, while spent implies both physical and emotional exhaustion. Drained indicates a loss of energy or vitality, exerted suggests that one has used up all of their resources, weakened implies a loss of strength or power, and flagged suggests a lack of energy or enthusiasm. These synonyms can help to add variety and depth to your writing when describing fatigue or weariness.