This is the choice I commended you on last time around.
Since my FIL's ordeal, each member of my family, and my husband's family have seen the importance of three documents and we have these documents for even the "young adults."
They are:
Durable Power of Attorney
Health Care Surrogate (my parents chose my husband, their son-in-law as their health care surrogate after they saw how he handled his father's illness, the lawyer found this strange, but we've been married 23 years, and I don't think he's going anywhere, LOL)
and of course, a Living Will.
Each member's living will differs a little, depending on what they have designated and the personal choices they have made concerning end of life issues.
It was uncomplicated, at least on a physical level, to deal with my FIL's illness because of the forethought he had put into his living will. No guilt or indecision about "were we making the right choices", we knew we were following his instructions
His funeral arrangements were also made and paid for in advance, and that, too, was a real blessing.
I learned so much through the entire experience.