" When we cooperate or look out for others, serotonin and oxytocin reward us with the feelings of security, fulfillment, belonging, trust and camaraderie. When firing at the right times and for the right reasons, they can help turn any one of us into an inspiring leader, a loyal follower, a close friend, a trusted partner, a believer . . . a Johnny Bravo. And when that happens, when we find ourselves inside a Circle of Safety, stress declines, fulfillment rises, our want to serve others increases and our willingness to trust others to watch our backs skyrockets. When these social incentives are inhibited, however, we become more selfish and more aggressive. Leadership falters. Cooperation declines. Stress increases as do paranoia and mistrust. "

― Simon Sinek , Leaders Eat Last