One of the most difficult obstacles in maintaining the motivation to run is the tendency to compare yourself with other runners. It can be difficult to accept when someone you know is able to run faster than you with less training.
In order to overcome the frustration of not running as fast as others, it is really important to understand how genetics helps determine running performance. The Florida Times has a good article on this exact issue.
The most important factor affecting endurance is the amount of oxygen the human body uses when put into motion. Aerobic capacity, or VO2 max, is the maximum amount of oxygen your body converts into energy.
Aerobic capacity is the best measure of fitness. The lungs take in oxygen, which is absorbed into the blood and pumped around your body, replenishing the muscles. The more oxygen used by the muscles, the better one’s endurance.
There are certainly things you can do to improve your aerobic capacity (training runs, speed workouts, etc.), but there’s no question that some people start with a higher capacity than others, and have an innate ability to increase their capacity at a higher rate.
The article has interesting estimation of the number of people who have won the genetic running lottery.
When you put natural fitness and trainability together, 5-10 percent of the population start with high aerobic capacity and 2-10 percent are high aerobic responders.
The odds of having a high aerobic baseline and a rapid training response — put another way, starting fast and getting faster — are exceedingly slim, between 1 in 100 to 1 in 1,000.
While seeing 1 in 1000 odds can be demoralizing, I would rather view it as a great explanation of why some runners are faster than others despite similar training.
Perhaps the most important lesson is that, in order to get the most out of running, compete against yourself instead of focusing so much on other runners. This is the best way to enjoy long term satisfaction with running.