Governance of Living Wills can be found in Florida Statutes 765.301 through 765.309. In Florida "any competent adult may, at any time, make a living will..." To be competent, a person must be of sound mind. The Living Will must be signed and dated in the presence of 2 witnesses. One may be a spouse or blood relative but the other witness cannot be. Keep the original in a safe place and let your health care surrogate know where it can be found. I also recommend providing a copy to your health care surrogate as well as with your physicians and hospital(s) you attend. Section 765.303 has sample Living Will form that is acceptable in Florida. Keep in mind, however, you can customize the language to accurately reflect your intents. In addition to a Living Will, I strongly recommend you execute a Designation of a Health Care Surrogate (Durable Power of Attorney for Health Care), a Springing Power of Attorney (used for financial decision in the event you become incapacitate), and a Will (a will should be done even if you have a Living Trust).
Living are great if they can be abided by. You might want to do a Health Care Surrogate with a HIPPA waiver so that someone is appointed to handle what will be your end of life decision. You can go to the FLABAR.ORG website and the information you seek can be found. However, I suggest you contact an attorney to prepare this for you. Afterall, this is your end of life decisions you are talking about. (Remember the Terry Shiavo Case?)