Motivation: the reasons one has for acting or behaving in a particular way; the general desire or willingness of someone to do something.
I believe that if you were to take a good look at ANYONE who has been very successful in ANYTHING, you would find that they have a great deal of motivation. No one continues to work tirelessly as something without a reason. For continued, heartfelt effort there must be a motive. The more important the motive is to someone, the more they will put in consistent effort. Their desire and willingness to put forth such effort will increase.
Motivation is the thing that makes one runner call another runner "hardcore." When you are motivated, other will ask you, "How do you do it?" referring to mileage, early mornings, grueling workouts, refraining from beer or sweets. There is more than a willingness to set the alarm, run the miles, finish the last rep fast, or forego the IPA. Deep down there is a desire. When you're motivated, you can come to realize that you would rather get up while it's still dark, drive to the track and grind out a workout because you want your whatever it is that is motivating these actions more than you want the sleep, or the comfort, or the beer.
And so, the simple question is: What is your motivation?
Motivation can come in many forms. Three people can all pursue the same career while being motivated by different things; one person can be motivated by money, another by personal interest, and the other by a desire to help people. In running, there are countless motivations: weight loss, healthy lifestyle, racing your best friend, racing your former self racing your competitors, $$, healthy lifestyle. Maybe you have a goal: to run the Boston Marathon, to run a sub-5 minute mile, to finish a 5k or a half or a full marathon. Maybe a Boston qualifier is just not a motivating factor for you right now, but you're running a half marathon this summer with your cousin Lindsey and it would be greater than winning Boston if you could beat her! Your motivation is going to be at least a little bit different than everyone else's, so find what motivates YOU!
If you have a goal, and you're motivated to achieve said goal, (and that goal is realistic), then odds are you will achieve it! "Done. I ran a 5k like I wanted, so that's it for me I guess." Ugh! No! As you pursue and achieve goals and your running progresses, so must your motivation. If I was still motivated to run a sub-2:45 marathon (a feat I once doubted I would ever do) I would not be nearly the runner I am today. I'm sure I would have lost ALL motivation and would have never discovered the runner I can be. Instead, my motivation shifted forward, to new goals. The same day I demolished my sub-2:45 goal I set both immediate and long term goals. I've smashed through those immediate goals and am still working on the long term goals. Actually, the long term goals I set that day are currently my immediate goals and I have since set NEW long term goals. These goals keep me MOTIVATED. Finding what motivates you is something to practice not just once, but again and again, week after week, year after year.