Motivation: What drives you ?

What are the true driving forces for motivation? Previous thought is that motivation is simply the drive towards pleasure or the drive away from pain. However as we grow we find motivation is more complex. My thought is that human motivation is a mixed bag of how close a person is to achieving a goal and how far that person has come. Consider that instance when you were working on a project and you anticipated you would receive a standard response. However your supervisor says "Excellent Job !!"
The next time you are working on a similar project you feel a bit more motivated. Two things happened here. 1. You may have discovered you have a talent for whatever that project is. 2. You find yourself working with more passion because you now have evidence you are capable of doing an "Excellent Job."
Society has shown us as a reflection of basic human nature that it's definitely more impressive how far someone has come rather than what they accomplished. Consider the story of the veteran that completed the Boston Marathon with one leg. Sure, there were marothoners that ran personal bests and even a first place finisher. However, the "real story" is the guy that did it with one leg and and an adult on his shoulders.

It's no small feat to running a marathon. Most people would agree that when they reach the finish line they are most interested in crossing that line than anything else. This veteran however reacted to his duty to serve and became more motivated to endure and finish.
Rules of thumb have supported this theory that motivation is enhanced by how close one is to finishing and how far one has travelled. One physical theory is that of "runner's high". At a certain point runners have travelled so far it's easier to keep going that to stop. Other supporting evidence is that it takes more energy to improve on something that someone is already good at that to improve on a task someone is poor at. Consider in the workplace that managers tend to seek talent to "train up" rather than laboring with those that may not show that same talent.
Essentially motivation can be created by reflecting on how far one has come and setting attainable goals. Once a person reaches that goal it becomes easier to reach the next goal and motivation is Enhanced.