Regardless of your age or health, it is never too early to look at advanced care planning.
These sites are from various sources and in no particular order;-
Five Wishes for Adults (also forms for adolescents, young adults and children) http://www.agingwithdignity.org/
Dying Matters: raising awareness of dying, death and bereavement – UK-based, but for all http://dyingmatters.org/
The Conversation Project: talking about the end of life http://theconversationproject.org/
Living Wills now Advanced Directives http://www.macmillan.org.uk/Cancerinformation/Livingwithandaftercancer/Advancedcancer/Advancedecisions.aspx
Good Funeral Guide – UK – http://www.goodfuneralguide.co.uk/
Compassion in dying, supporting your choices at end of life http://www.compassionindying.org.uk/