Research suggests that when we stop the process of pursuing a goal, we are often very close to reaching the goal. I believe it is because the process slows towards the end and that frustrates us. Don't stop, the big reward is on the other side of the big obstacle.
We should be setting goals that stretch us and are difficult to achieve. In doing so, we must also realize that the journey to these goals will slow down and be most difficult toward the very end. That's when we need to fight the urge to give up simply because it's taking longer than we expected. Commit to finishing strong.