Human tribes have been warring for at least the last several thousand years. We are descended from the tribes that were able to field the largest and most cohesive armies. That is to say, we all have war in our genes.
But as humans filled the globe and as the technologies of destruction made war ever more deadly, the human race has been gradually coming to its senses. General Sherman taught us that "war is hell". General Smedley Butler, the most decorated Marine in U.S. history, came later in life to teach that "war is a racket." And General Eisenhower prophesied, "I think that people want peace so much that one of these days government had better get out of their way and let them have it."
Nowadays, David Swanson teaches us that every war has been founded on lies. That is to say, if our leaders or our news media were telling us the truth, it would not be possible to brainwash enough people into the insane proposition that they ought to participate in mass murder.
So, what can we do, you and I, citizens of the greatest military power in the history of the world (fact) and the world's biggest bully (my opinion)--what can we do to promote peace? My belief is that the spiritual truth, "peace begins within you" can be misleading. Working on ourselves to achieve inner peace is of unquestioned value, but we cannot wait until we have individually tranquil inner lives in order to begin the collective work of organizing an end to war. The few who benefit from war are exquisitely organized, working together in what we might call a conspiracy, if the word hadn't been discredited by our own CIA. We must be organized. We must take concerted action. We must resist the temptation to wage war in the name of peace. We must be firm in our resolve, but never coercive. We must be persistent in our vision, but not necessarily patient; I think that our cause is too urgent for patience. We should demand peace, now.
Don't neglect the capitalist connection. The major reason for our country being the world's greatest war monger is that war is profitable for banks, for defense contractors, for fossil fuel companies. There was a sweeping movement in America of the 1920s to take the profits out of war, culminating in a bill introduced in Congress in 1935 to take the profits out of war, and it nearly succeeded in passing. In 2007, a War Profiteering Act passed the House, but not the Senate. You can bet your bippy that if for the largest international corporations peace were more profitable than war, we'd have peace.
Get out and organize peace demonstrations. Talk to people you know and people you don't know. Tell them you think war is insane, even as it is pushed as "normal" by almost every politician and every news pundit. And meditate on peace, pray for peace, visualize peace. Yes, there is real evidence that collective intention has power even apart from its psychological effects on the individuals involved. Go figure.