I started out not being able to run 10 minutes, but started with 7 minutes. Soon I could run 10, then 12, then 15. At the end of my first year of running, I ran a marathon.Actually, this is exactly what my wife did in 1982 when we were stationed at Fort Sill, Okla. I was already running, of course, being in the Army. Cathy decided to take up running as well. So I took her to a high school track. She ran around the track at a comfortable pace until she felt it was time to stop.
She made two laps in 7-1/2 minutes and stopped, exhausted.
So the next Monday she ran eight minutes, then:
Tue: 6 minutes
Wed: 10 minutes
Thu: 7 minutes
Fri: 12 minutes
Sat: 15 minutes, but deliberately slower (an "LSD," for Long Slow Distance)
Mon: 14 minutes
Tue: 8 minutes
And so forth. If you plot this out on a calendar, you will see that you reach 60 minutes of nonstop running in not many weeks. Cathy started in April. In October she ran a marathon and finished second. By then she usually left on her Saturday-morning run at 6 a.m. and returned home at noon, having run nonstop for six hours.
With my military duties I could not devote that kind of time, but I did work up to a half-marathon.
The hardest part is not the running. It is putting those shoes on at 5 a.m.