Many people start running to lose weight or get fit but then begin to love running for it's own sake.
Tom Holland, running coach and author of "The Marathon Method," tells his clients that running for 3 miles was horrible for him too, but farther down the road things changed.
"It happens for different people at different times and different distances: that runner's high," he said in an interview.
For me the three-mile distance was the turning point. Getting myself in shape to run three miles seemed hard, and three miles felt like a million. Once I gained the ability to run three miles it was pretty easy to add on more miles. I don't think I've ever hit the wall even when I ran my half-marathon, but there was definitely a hump at the three-mile fitness level.
Why do runners love to run? There are a lot of reasons, but one of the top for me is that it's so linear.
Gregory Chertok, a sports psychologist with the American College of Sports Medicine, said many people are drawn to running because it's an uncomplicated activity.
"Put one foot in front of the other and when you work hard, you improve," Chertok said. "Not everything in life is so simple. You could spend 10 years in a ballet studio and not become a ballerina."
If you run longer, harder and faster you will become a better runner. You may never get a promotion from working hard, you may never win a prize, and your kids may end up in jail despite your best efforts... but you can get as good at running as you want to!