My brother and his girlfriend were kind enough to run/walk with me at my pace. We finished in 40 minutes. I have probably been at around a 15 minute-mile pace on my shorter runs, so it looks like I probably shaved a minute per mile off, in the much longer run.
During the second half of the 5K, my running intervals were very short. It was a stretch just to run for five minutes during those times.
I feel good.