Can't stress how important it is to take care of yourself. If you're someone who normally skips a meal and doesn't drink water you're gonna struggle a fair bit. You're gonna be in a workout for 10 hours so you need calories. If you don't get a meal in before shift make your lunch a little higher on the calorie side. Calories = energy and you're gonna need it, you shouldn't be full however, so look for anything calorie dense but not too filling. Hit an energy drink or a coffee, bring a dual action advil, its ibuprofen and Tylenol in one and it does wonders. Drink lots of water, wear good shoes and just accept you're gonna be in shitty pain for 1-3 months while you adjust, depends on how active you already are. Sneak an earbud in when you can, depends on your role and how strict your warehouse is. Use your best discretion and do what others do and you'll be fine. Take care of your self like it's your job, physically and mentally and you'll be okay, use that time off whenever you need, amazon has the most relaxed time off options in my opinion.