The Walking Dead has seen many characters come and go, but only a handful remain that have managed to survive this zombie apocalypse throughout its three-and-a-half season run. One of them is Glenn, portrayed by Steven Yeun, who reminisces about his time on the hit AMC series in a new featurette. The actor talks about how Glenn is driven to survive, while pointing out some of his character's dumbest moments. Plus, he gives out a few survival tips and lists some of his favorite Glenn moments. Learn more about this pivotal character before the series returns Sunday, February 9 at 9 PM ET with "After".