I worked as a courier for a short while, and I have good memories of that time. It gives a certain kind of job satisfaction which is very different from what y

I worked as a courier for a short while, and I have good memories of that time. It gives a certain kind of job satisfaction which is very different from what you get from being... well, anything else I've ever been. Your goals are short-term (get this package to that place by this time) and achieving each one gives you a little dose of satisfaction. If you get to the end of the day and you haven't been late, lost a package or been hit by a car, you know you've done your job as well as possible. That's in stark contrast to being, say, a theoretical physicist (or a software developer), where the doses of job satisfaction are (hopefully) much larger but are much further apart, and where you can easily go for days without feeling like you've achieved anything.