You do have the power to control your own stress response. Plan your response to stress. Certain events in your life are repeated, and you can learn to anticipate a crisis. Determine that you will manage the next one with greater calmness. Treat yourself positively.
Worry is neither profitable nor constructive.
Do what you can about a situation, and then move on to other things. Affirm to yourself that you do your best, that you do all you can, and that things will work out well. This is much better than negative, hand wringing indecisiveness. Work on being open and politely assertive. Suppressed feelings, anxieties, self doubts, and low esteem are among major stresses that lead to illness and disease.