I'm new to running (casually started last year, running on & off). I've since run a few 5ks & 10ks. My weekly mileage is ~20 miles/week with longest run of 15 miles.
If it makes any difference, I've done all of my training w/out taking anything with me (gu, water, gatorade). I just completed a half-marathon in two hours flat with negative splits and didn't feel much leg pain until the last couple of miles.
My first full marathon is in three weeks. I completely mismarked it on my calendar (weeks earlier than I had initially thought) and also missed a couple weeks of critical training (prior to the half marathon).
I realize I won't be able to run the entire thing but really hope to at least finish by adopting some sort of strategy like alternating running/walking and not be miserable.
Can I expect to finish the marathon?
What should be my walk:run ratio and/or pace to safely finish based on the half?
What sort of training if any can I do the three weeks prior?
EDIT: I've read this post. I'm asking more about how or if I can finish rather than whether or not I should try.
UPDATE: I finished the marathon (on five hours sleep with a long run of 18 miles). I ran most of it. The first 15 were a breeze. Had some ups & downs for the following 6 miles. The last 5 miles were a bit rough but at that point there was no turning back (and I was so happy with the running community's encouragement when we crossed paths!). Felt good to cross the finish line in a reasonable amount of time. It was definitely mind over matter at that point though, I look forward to running another one with proper training and beating my time!