The year before I went to university there was a brief period when I was working seven days a week. I had a Monday to Friday job labouring in a factory, and I was still working the weekend job as an industrial cleaner that I'd been doing for a couple of years whilst doing 'A' levels. I think my seven day weeks lasted for a month and a half, and then I knew I had to stop. Even for a relatively fit teenager it was too much, a kind of tiredness you couldn't recover from.
I'm feeling a bit that way now, but nothing close to that extreme. There's an element of physical tiredness involved, but the mental variety I'm suffering from now doesn't have the devastating quality of true physical exhaustion.
Which leads me to wonder how those guys who work two jobs, the minimum wage crowd, often with families they're looking after, get through it all. Painfully I should think. Certainly with a deep, crowded, unforgiving weariness.