I have found that when getting to a certain point, I feel the urge to let up. Even stop and look at where I stood then, versus where I stand now. That's when it seemingly harder to get moving again; it's not getting going so much as it's returning my focus to moving forward. Now, I have learned that no matter what, do not stop or slow down too much. This does not mean rushing from one goal to another, but to be present enough to know more must be done in order to achieve the current goal.
The same thing can be said when meeting opposition; failure and everything they encompass. It reminds me that no matter what - keep moving forward; keep pushing and never, ever give up. The Japanese say: "fall down seven times, get up eight" and just shows good cause to keep on fighting, pushing, doing. Our life is shaped by the actions and ultimately the results of those actions; that is why it is so important to do our very best.