I know this sounds counterintuitive, but start working out. Find a good routine that works for you, start eating a little better (find some nice protein, not even shakes but even just chicken breasts or protein rich nuts), and once you get past the initial soreness (get plenty of sleep, this is critical!), you're gonna see an improvement in your stamina.

Someone here once posted that they would make themselves go on walks after shifts and it would just boost their energy levels. If it doesn't work for you, that's fine. If you try and it doesn't work, at least can say with confidence you're trying all angles.

I feel the exact same. I’ve been having nightmares that keep me up, unable to fall back asleep and thinking I’m still in the store, stupid hours every day, throwing myself into exhaustion mode every day and breaking down after every single shift. Plus I overworked myself and couldn’t even walk right because of my back and I always limp after a king shift with $25 insoles

Yes. This kind of work is literally destructive to the human body-- even DT/reg is terrible for your body because literally standing in one place for hours is murder on your joints and back.

The more walking you can do the better off you'll be. Also, taking a min every 30 to squat down and stretch your legs/lower back will help.