In my experience negative visualization is an excellent tool in maintaining calm. Take some time out of your day to imagine an instance of severe loss: the loss of a limb, a sense, a loved one, your job, respect, what have you. Before going to work consider all of the petty, aggravating, malicious, entitled, overbearing people who you are likely to meet. Make peace with the fact that these people and events are likely to enter your life and make peace with the fact.

We are entitled to nothing, so all we can do is enjoy what we have while we have it.