When you work in retail, people are always fucking your shit up. You will pick up some amazing folding skills, only to see your perfect stacks get reduced to a huge pile of shirts by some asshole looking for size "doesn't exist." This doesn't change when you get older. Sometimes a co-worker will forget to carry a zero on a spreadsheet, sometimes your boss will skip town with the secretary and leave you to meet with a huge client and warn you not to fuck it up. Just keep your cool. These things happen sometimes, and what you'll come out of it with is grace under pressure.
8. You'll sometimes have to clean up other people's messes