There are days and prospects that seem overwhelming...almost Everest like in size and difficult. Hillary, the climber noted, and I'm paraphrasing, that the closer you got to the summit, the nearer the goal, because of the lack of oxygen and the accumulated stress on your body and mind, the harder it got...no "end is in sight" and a surge but just hoping not to collapse before you get there...marathons are much the same.
So take a few. Regroup.