I worked for over a year as an overnight security guard. I was on my own 90% of the time, and there was no real danger involved. Us guards were essentially just narcs, and if anything DID happen, we logged it and called the police (if necessary). I got great exercise walking all around, and took off 70 pounds in about 6 months.
Another job I did (immediately prior to security) was as a bookkeeper. I processed the daily sales of stores and ran the numbers through an Excel spreadsheet. Easy-peasy. If the numbers didn’t match, I ran a report, and compared the two, found the discrepancy, and that was mostly it.