Absolutely true. You don’t possess a bottomless pit of willpower. It’s why New Year’s resolutions fizzle out. It’s why you can only resist easily-accessible snack food for so long. Anything that takes mental effort drains your resources and without time to recuperate, eventually you’ll have nothing left.
Winning is easy. Winning is no effort at all. Once you’re ahead, you need little motivation. You can just play. Losing is hard. Trying to motivate yourself when you know, deep down, that you’re already unlikely to win takes rather a lot of effort. Find yourself in that position for long enough and eventually the well will run dry.
After day one of the second Test, Australia were 337-1. Clearly they hadn’t won, but they were massively, massively ahead. Maybe England retained a 10 per cent chance of victory. It is harder to motivate yourself when you only have a 10 per cent chance of victory.
At the end of day two, Australia had made 566 and England were 85-4. They probably didn’t even have a one per cent chance of victory now and they had maybe a 20 per cent chance of salvaging a draw. It is hard to motivate yourself to play for a draw. It is harder still to play for the outside chance of a draw.
At the end of day three, Australia were batting for a declaration and there was nothing England could realistically do but wait and maybe try and slow them down a bit. It is very hard to motivate yourself to try and slow down the opposition in the hope that you might postpone their declaration for long enough that maybe, hopefully, some bad weather will arrive and save you.
On day four, Australia declared. England needed 509 to win and they needed to find some resolve.