Try to put off major decisions. Set your own limits and learn to say no. It is common to experience physical reactions to your grief, e.g., headaches, loss of appetite, inability to sleep. Go to bed earlier. Try to eat balanced meals because good nutrition is important to the healing process.
Exercise is important.
It provides a physical outlet for emotions. There are many helpful books available on the grieving process. Understanding grief makes it a little easier to handle. Holidays can be especially difficult. Schedule activities that you find particularly comforting during these time, and be careful not to overdo.