The phrase "choke up" refers to the overwhelming feeling of sadness or emotion that makes it difficult to speak or breathe. There are several phrases that can be used interchangeably to express the same sentiment. "Get emotional," "tear up," and "well up" all describe the feeling of having a lump in your throat or feeling like you are on the verge of crying. "Be overcome," "be moved," and "be touched" describe the feeling of being deeply affected by something. "Falter," "stumble over," and "get tongue-tied" all describe the difficulty speaking that comes with being choked up. All of these phrases capture the feeling of being so moved by something that it feels like your emotions are physically affecting you.