You are motivated primarily by competition. How far and how fast you run is largely dictated by meeting the needs of your racing, and you think of running in terms of training. You would still run if you had to give up racing, but not nearly as intensely.
Your main motivation is running for running's sake--you like how it feels and how it makes you feel afterward. You might race, you might not. Running is part of your routine; it makes you feel complete. How far and how fast you run is based more on how you feel that day, your perceived needs, how nice of a day it is, and your surroundings. You hope to run a decent amount pretty much every day for the rest of your life.
You do a fair amount of racing, but you're drawn more by the social aspects of the events than your competitive drive. You're probably in a running club, and you're likely to volunteer at races.
You run primarily for the quantifiable physical benefits, such as weight loss and disease protection. You think of running more as exercise than as something that's a natural part of the day and are likely to skip it if life's obstacles make it inconvenient. You likely to cross-train. You're not likely to participate in races, but you might sign up for one if it benefits a charitable cause.
If you have a chance get the magazine, take the quiz and read the details that I left out of the four types of runners.