Sometimes, there is nothing left to do but push through a task list until you run out of steam, time, or open eye lids.
When that happens, I open my planner, do everything I can do from the quickest tasks first to the most time-consuming last, and only stop if I pass out (okay, not literally) or cross the finish line.
TIP: Cross out the completed tasks will a highlighter so everything that is left jumps out at you.
I call this method marathoning. Everything else is just training for marathon days. Only the toughest will survive. Oh, and those with a plan and a planner.