Mario Guerrero, a black belt, has made a name for himself in the martial arts world for helping at-risk kids by giving them training in discipline, fitness, and hand-eye coordination. He now has studios scattered throughout the city, from Tribeca to the Upper East Side, where children and adults alike can learn kickboxing, Brazilian Jiu Jitsu, and Mixed Martial Arts. Recently, Krav Maga, a form of Israeli street fighting, has been added to the roster. Modern Martial Arts advertises classes for everyone from "casual fitness seekers to trained, professional fighters. " The studio does more than offer classes; however: they also create a community. Mario and his trained teachers offer karate birthday parties, fitness-centered movie nights, and "Parent's Night Out" evening classes for kids. We met with Adam, who was teaching an adult mixed martial arts class. He greeted each of the students who walked in with warmth and humor. Once the class began, the group transitioned from generic fitness exercises to work with punching bags and finally horizontal punching bags where the studio members practiced their "ground pounds. " Watching Adam encourage his students to let out a "pshhh" sound each time they hit, I realized that the class was a terrific way to let off steam.