A couple of observations. Spokane (WA) has a 12K road race (Bloomsday) every May that attracts approx 40,000 entrants, ranging from elite runners competing for a monetary prize to causal walkers and joggers. Last year I saw a woman wearing a shirt that said "13.1 I am only half crazy". Since Bloomsday wa already a liitle more than half the distance of a HM, I decided I would do a HM this year, aiming for the Windermere event that features both a full and half marathon on an essentially level course along the Spokane River.
My training involved increasing the distance of my long runs slowly (a couple of minor injuries caused setbacks in training) up to a distance of 12 miles two weeks before the HM. I did find myself running out of energy during the long runs on occasion and did include adding a GU refuel while running. I also carried a couple of them with me during the HM. If you do decide to use any type of nutrition during the HM, use it in training as well so your body learns to handle it.
Long story short, while I didn't meet my desired time, I did finish the HM (the primary goal), and rewarded myself by ordering my own "13.1 because I am only half crazy" shirt 