By not looking for it.

Peace is a state of mind which is as fleeting as water in a still pool. Grasping at it will only produce ripples and leave you with an empty hand.

To attain peace, one must first set aside all the cares and worries which this world continuously and insistantly gives us to shoulder.

There is a meditative technique called 'finding your center'. In short, it is a quest for self-identity. Once you have your self-identity, then you may find peace, for that core of stability within you will not be rocked by anything the world will be able to throw at you. Only then can you proceed to a more peaceful state of mind.

This is the zen of tranquility, a state which most of the followers of the zen philisophy strive to attain.

Of course, this is easier said than done... I'm still working on it myself.