"Your left, your left, your left, right, left!" Marching in perfect synchrony is the first thing every soldier must learn. Many recruits consider the exercise an annoying way to teach obedience, but drill sergeants say marching produces better soldiers by improving not just discipline, but also morale. According to a study published online today in Biology Letters, the drill sergeants may be right. The researchers started by making the male subjects walk 240 meters. They were randomly chosen to walk either at their own pace or in synchrony with another male. After that they were shown a "criminal"—a mug shot of an angry male face—and asked to fill out a survey about their feelings. As previous studies have shown, walking in synchrony made men slightly happier and more friendly toward their fellow marchers. But surprisingly, the synchronized marching also affected how the subjects perceived the physical attributes of the criminal. After marching, men judged their foes as smaller and weaker. So if you're feeling intimidated, find a buddy and go marching. It really will boost your morale. As a bonus, if you have thousands of buddies willing to march, like these North Korean soldiers on parade, you'll be a terrifying spectacle.