No, that's practically accurate. I can walk a mile in probably 14:00 if it's really level and I work at it. So a 12:30 mile is not exactly "running".
Today was better though, same routine, walk 5 min, run a mile, walk 5 min. This time the mile was 10:17. It was a piece of cake too, I just chose music in the 165 bpm range and kept time with that. That's a serious pro-tip imo, I have playlists for music at a bunch of bpm ranges. Keeps my mind occupied and it's really hard (for me at least) to run out of time with music. Heart rate was right around 160 the whole running part.