Read the living will carefully to make sure it meets your needs. This document will be legally enforceable if you are suffering exactly in the way you have described and you have lost the mental capacity to communicate your wishes to your health care professionals.
It is a very important document that could dictate the end of your life. Be sure that it meets your particular needs and make sure that you have discussed it with your doctor and your family. Remember that if you have any questions you can easily Ask a lawyer.
You should also Ask a lawyer if you are unable to physically sign your living will. It is still possible for you to complete a living will but a different clause will need to be added at this point depending upon your individual circumstances.