Go From Breakdown to Control - Breathing Space Blog
Take mental pauses throughout the day, particularly as new developments occur. The best laid plans often go astray and those people who are able to maintain control know when to let go of one activity and redirect their focus towards another.
Remember that being in control is more related to how you feel about the situation than the presence of evidence. Keep reminding yourself that you are, in fact, in control. Ten minutes before the end of the day if your boss springs a one-hour assignment on you that must be done immediately, you can regard this as a major intrusion in your day or you can see it as a professional challenge or an opportunity to demonstrate your overall value to your company.
Make a note of the times you have taken on such challenges and bring them up particularly at raise times. Also before, during, and after handling the late assignment thrown on your lap, keep considering the many benefits of completing it. These include learning something new, practicing maintaining grace under fire, and serving as a reminder for you to discuss this type of situation with your boss so that it doesn't happen too frequently.