If you're young and need to develop an estate plan, it can seem premature. After all, you may have decades to live before you even have to worry about the kind of protections that an estate plan provides.
The thing to remember is that life is unpredictable. You want to guarantee that those around you know what you want and expect when you can't make decisions for yourself.
One of the most important documents to have in any estate plan is your living will. Combined with your medical power of attorney, you'll be able to have someone make decisions for you when you can't do so for yourself. They'll be guided by (and restricted to) your wants and needs as listed in your advance directive (living will).
Why is it important to appoint a medical power of attorney?
Imagine getting into a car crash. You have a serious head injury and go into surgery. You have no ability to tell anyone what you want or don't want.
Your medical power of attorney can come to the scene and talk to the doctors. They can decide if you'd want a series of operations that could help or refuse them if you only wanted life-saving procedures and nothing more. They can make hard decisions for you when you can't do so.
That's just a single scenario where they could be of help, but it makes it clear why you need someone there for you in trying times. Our site has more on a medical power of attorney and what you should consider when appointing one.