When we face these situations exhaustion is the only thing on our mind. We just want to sit down and stop, relax, put our feet up, or drift away into social media or the TV. However if we can just get started the energy will come. Find that thing that moves you and focus on the work. Put on the music, or create complete silence, whatever you need. When exhaustion is upon us we need to know ourselves more then any other time. What is your inspiration, what is your motivation.
Music moves me and the desire to see completion. Late in the day when my willpower is weak I need to dig deep, to know my inner most need to see a job completed. I plug in the music, put in my ear buds and fall into the music. I take a moment to drift away, and then open my eyes and look at the work ahead. I have found the job with the least thought needed and I drift into my work. Sometimes it is 30 minutes sometime I realize 2 hours has drifted away but the work is moving forward. I have found my focus and I have moved a project forward.
This comes to more then just focus, more then just inspiration it comes down to organization, it comes down to knowing yourself. If you can organize your day, structure it with the heavier thinking early in the day, move toward the mechanical work at the end of the day. Know your high points and know your low points. Understand how you will process through the day. We each only have only so much willpower each day, we can build that over time but still only have a set amount to work with. When we see those people that seem to have amazing amounts of willpower it is not magic, it is logic, work with your strengths and work with your weakness. And when all energy is gone, find that work that will let you drift in and out and just get the job done.
Motivate, inspire and find your focus.