A living will is a legal document that explains what types of life-prolonging medical procedures you want or don’t want if you become incapacitated.
It is usually drafted in connection with a durable power of attorney for health care, which lets you name a person older than 18 to act as your patient advocate and carry out your medical wishes if you can’t .
Both of these documents are known as advance directives. They need to be written while you are of sound mind and generally witnessed and notarized. Laws vary somewhat by state.
Look online for sample living wills and durable powers of attorney for health care for your state. Many state bar associations have them for free. You can also find them for free or a nominal charge at http://www.legaldocs.com/ep_ind-s.htm.