It is difficult to stay motivated all the time, because it requires making conscious efforts. Thoughts about past and future come back from time to time, making it very difficult to concentrate on the present moment and not to worry about things you can’t change. Plus, every person gets trapped in a “psychological pit” sooner or later. The ability to get out of that pit is what differs average person from the great one. If you know how to motivate yourself, you’ll do few times more and better than the person which just stays with the crowd.