I grew up playing war. We threw dirt and rocks at each other. We'd lead attacks. We'd break up into squads. It became a neighborhood thing for a while, our neighborhood against the other neighborhood. There was always a war breaking out somewhere.
Be unselfish. That is the first and final commandment for those who would be useful and happy in their usefulness. If you think of yourself only, you cannot develop because you are choking the source of development, which is spiritual expansion through thought for others.

