Acceptance

Acceptance is the opposite of rejection or resistance.

Acceptance keeps your mind calm and positive. As William James said, "The starting point in dealing with any difficulty is to be willing to have it so."

The moment you accept that a change has occurred and that you can't prevent what has already occurred, you become more capable of dealing with the change and turning it to your advantage.
One of the best ways to deal with the worry that is often generated by unexpected change is to sit down and answer, on paper, the question: "What exactly am I worrying about?"