Your health care proxy is the person you appoint to step in as your substitute decision maker if you are unable to manage your care or it may be the person your state law specifies as your default proxy (a "statute by proxy") if you don't preserve your wishes ahead of time.
So, imagine yourself with a life-threatening, terminal condition or in an irreversible unconscious state and the doctor looks around the room, waiting for someone to tell him or her whether to (fill in the blank) insert a respirator, give you artificial feeding or hydration or perform a medical procedure that might prolong your life.
If that time comes, who is the person you hope will be making that decision?
An adult child?
A good friend?
It's no small thing to choose the person who is available, willing to serve, familiar with your wishes and--perhaps most importantly--equipped to act as your advocate. Being your health care advocate means asking the right questions, considering the choices with your wishes and best interests in mind and doing whatever is necessary to see that your rights and wishes are respected.
Did that narrow your field of choices?
Please take some time to consider your own wishes for care, communicate those wishes to your loved ones, choose an appropriate proxy and document your wishes and your choice of proxy.
That's the advance part of advance health care planning.