Running is all about motivation! When you feel like you're about to reach your limit, do you give up or carry on? If your answer is to carry on, then you were born to run; if you'd rather give up, then running will help you overcome your weaknesses in the long run.
It's important to set realistic goals when you go running. Set the bar a little bit higher every time and you'll soon find that you're capable of things you didn't think were possible. This attitude carries over into many areas of life, by the way: whether it's at the workplace or in their personal life, runners tend to have a can-do approach that people will respect.