Just read the first 40 or so pages of the book Outliers by Malcolm Gladwell. It's really interesting so far, and right now it is talking about the correlation between practicing a skill and the level at which you can perform that skill.
They noted that elite violinists had accumulated 10,000 hours of practice by the age of 20, the "good" players had accumulated about 8000 hours, and the average players had only practiced for about 4000 hours. This was consistant for many, many different learned skills. Music, mathematics, computer programming, skill based sports such as basketball, soccer and ping pong. Basically, they found that natural talent helped get you into the talent pool that was divided up into performing a task at moderate, exceptional and incredible levels. The only difference between those levels was time spent practicing.
The researchers could not find someone who was among the very best who did not spend a massive amount of time practicing the skill, and they also could not find an individual who spent the necessary years practicing the skill who was not among the elite performers. Virtually everyone fell along the same line relating work to results. Even Mozart, who was supposedly the greatest child prodigy of all, did not complete his best work until 20 years of composing several hours a day. His "natural talent" was nothing more then an incredible workload over an incredible length of time.
Does this apply to running?