At least a dozen good Samaritans in New York City have risked their own safety to save a stranger this year. Personal trainer Dennis Codrington is one of them. He jumped down onto the subway tracks to save an unconscious man as the train barreled down in February. He says he was just doing what was right. But psychologists say it takes a certain set of character traits to make someone leap down onto subway tracks, including altruism, courage, knowing the right thing and being reflexive about it, as well as the ability to inhibit fear that stops most people from getting involved. Codrington doesn't know what happened to the man he saved, but he hopes he survived and is healthy.