<human>: Give me the gist of the text in a nutshell

I've started working as a picker in a warehouse for a well known internet seller and it's slowly killing me. I've gone from no work to working 11 and a half hour shifts 5 and a half hours a week. The work includes a good 10 miles of walking, a lot of bending/squatting, pushing and lifting and constantly being on my feet apart from a couple of short breaks. 

Combined it's left me in a large amount of pain which in turn is slowing me down at work, which is making me force myself harder, which is causing pain.. you get the picture. I know a lot of the pain in my muscles is just from me being a lazy sack of shit normally and it'll go away eventually, but with little time to rest the muscles, how can I help the process? As a follow up, best way to combat rash between your legs? I used to hill walk but never really suffered from this. And is there away to keep my feet from getting sore, stretches or such like, ways to relax while standing?
<bot>: unfit, got job, jobs kicking my unfit ass, please help. I'm back in in a little over 6 hours, I'll take anything!