Refuse to 'let it bug you.' You respond to the stresses in life out of habit, and habits can be changed. Retrain your mind to respond to the same set of facts by telling yourself, in advance of a difficult scenario, 'I will not be bothered by, or overreact to, this event.' In the beginning this may seem superficial, but breaking habits takes deliberate effort. In time you won't have to remind yourself to respond to the little things this way - it will become your new habit!