There are a variety of synonyms for the phrase "grow excited." One alternative is "become thrilled," which implies an increase in enthusiasm and excitement. "Get pumped" is another option, suggesting a surge of energy and anticipation. "Become animated" conveys the idea that the speaker is becoming more lively and energetic, while "get worked up" indicates a stronger emotional response. "Become impassioned" suggests a deepening of one's passions or convictions, while "get fired up" implies an increase in motivation and drive. Ultimately, the specific synonym chosen will depend on the context and desired tone of the message.