Martin Luther King Jr. said that, and he was right. And his wisdom holds true not only for peace in our world, but for peace within ourselves.
All of our spiritual traditions teach the same thing. To achieve peace, be peace. Yet how does one be what one is wishing to experience? By a sheer act of Will.
And...by causing others to experience what you wish to experience.
Neale Donald Walsch
"Why do I consider it is so crucial to balance the outer aspects of nonviolence and compassion with the inner support of contemplative practice? Because in the end, all politics are local, and we cannot love life and humanity if we do not love each other, one on one."
Lama Surya Das