I am currently unemployed in my office job field, but I have an offer on the table. As with past jobs in this field it is 8 am to 4:30 pm with up to 1 hour for lunch (technically 30 minutes and two 15 minute breaks, but no one uses them that way). It also includes anywhere from 1-3 night meetings per month.
During peak at UPS I did in fact work 12 hour days. I had about 6 weeks in a row of 60 hour checks.
I have always been the type of person that is smart and professional enough to work in a white collar job, but physically fit and down-to-earth enough to work in a blue collar job. And in both I am a hard worker.
I could see myself working as a loader on the 5 pm to 10 pm shift while I have the office job, though I would have to be like Superman changing and driving from one to the other. I don't think I could do the 10 pm to 3 am or 3:30 am to 8:30 am shifts. I need to be able to sleep. In that regard I am not Superman.