Okay, I have a 2.5 mile loop around my neighborhood. I allocated 12 hrs to finish. It took me 10rs and 20 minutes, I started an hour late (I slept in a bit). I actually only walked for just under 9hrs. So I took a few breaks, I had to ice my feet. I had to change shoes to a larger size as they were swelling,but I avoided getting blisters! (I did chaffe my nips a bit, LOL. That’s actually a thing)
It took me a while. I failed at the 20 mile mark once before a couple of months ago. My BP Crashed and took me down. Doing it fasted… I used caffeine strategically this time to keep my BP elevated enough to get me through. I monitored at least every 5 miles. Later I stopped every 2.5 mile loop. It certainly gets harder as the day goes on. I also got a couple of rain delays.
So, it took me a couple of solid months (say 3-4) to train up to this. Keeping in mind that the first time I did 10 miles, I had blisters, and tons of problems, and was still finishing my weight loss efforts. 2 weeks before this, I did 10 miles like walking in a park. A tiny blister from a brand new pair of shoes! (Shoes I wore on my actual walk).
I alternated between walking daily (2.5 - 5 miles), and then EOD 5 miles, weekend pushes of 10-15 miles over 2 days, all fasting, taking electrolytes, and experimenting with things to keep my BP from crashing… A 5hr energy poured into a bottle of water, sipped while walking is good for about 7.5 miles, maybe 10, depending on the heat, etc.
I read about how to train for a marathon (Couch to Marathon, Couch to 5K) and based it roughly on that. Pulsing my workouts. The best part is that I am never more than ~1.25 miles from the house.
I will use this same route for my 50 miler push (I really should do 62 miles so I get 100km)… My wife is from Europe… LOL