In Tai Chi - indeed, in all martial arts - we say there are doers and there are talkers. I suspect it is this way among a wide range of pursuits, but we see it in martial arts a lot: a person who enthusiastically talks the subject into the ground, but never carries through on promises to pursue it for real. He'll come to a class and talk for a half hour before and after class about how enthusiastic he is and how much he loves the class and is ready to devote his life to Tai Chi, then never show for a second class.