I have a younger brother who is 22 and a recently recovered drug addict. Last year he expressed interest in starting to run, and I started training him in June right after my track season ended (I compete unattached).
For the first month I had him just walk/jog barefoot on grass everyday. This seemed fairly boring to him and I'm surprised he didn't quit on me. Then starting in July I would take him out for an easy 2-4 every day. Over next two months it gradually went from 2-4 to 3-5 and 5-6.
Then a few weeks ago he entered his first 5K, and I ran it with him. I didn't have any idea how fast to take him so I just let him run at his own pace and stayed with him. So he started at well under 6:00 pace and I thought he was going way too fast trying to impress me. Anyway, he finished in 17:34! The dude is 22, has never run a step in his life, is a former smoker and drug user, and, with less than three months of training and virtually no workouts, he runs a time that I hit during my sophomore year of high school, with a year of running under my belt.
I am a sub-15 guy and am not insecure about my status as the superior runner yet........ but, if he keeps up at this, i suspect that it is not out of the possibility that he could be coaching me in five years.