flat tire-dness
A state of fatigue so terminal that you cannot roll another foot, having all the shapely utility, bounce and style of a flat tire, the air completely taken out of you.
Another day, after another sleepless night, feeling so deflated that no air hose, pressure gauge or patch could address his flat tire-dness. Yet he'd get through it, for sure, he'd do everything needed of him, as he's done yesterday, and the day before, and the... day...... before........... huh?! Me?? Yeah, no, I'm awake! Just turn the key, give it a little gas... sure, let's go.