Tank Engine,
I’m going to assume you’ve talked with your doctor and gotten his or her approval to walk the AT. I’m also going to assume you have no hiking experience. Finally, as you say most of your weight is fat, I am going to assume that you are in terrible cardiovascular and muscular shape and that this has always been the case.
Based on those assumptions, my advice to you would be to cut your proposed distance by half at least, leaving you with a maximum of five miles daily early on. But, let’s go even further.
My suggestion would be to start with 1-2 miles daily; with the provision that you stop and rest whenever you feel the need or inclination. And as the runners say, if you can’t talk, slow down or stop.
Prior to going on the trail, start walking where you live, again, for 1-2 miles at most, and slowly. Just put on your coat and go out the door. No driving, no pack, no complications except wearing your hiking boots to break them in.
Some people start, literally, by walking around their home or backyard, once. There is nothing to be ashamed of, nor warranting frustration, by starting as slowly as you need to. The point is to continue daily and increase your range and fitness over time. As with so many things, “One Day at a time.”
It doesn’t matter whether you finish the trail. What matters is that you get on the trail and give it a go; in a manner consistent with your current state of health and physical condition; in a manner that does not threaten your life.
As the runners said so many years ago during the first running boom: “LSD: Long Slow Distance.” For you, now, even a short distance is long. Accept the truth of that, move slowly at first, with a light pack, and stretch your distance out over time. Let your body get into second gear on it’s own; which, believe me, it will; and when it does, you’ll feel good about it.
Best wishes.
Conan
Conan