UPS isn't a bad job if you like some exercise while you work.
I've been working part-time for UPS for about 4 1/2 years. I work at the airport with air mail so our operation is quite different than the UPS ground operation.
I think it is a good job for SA. All you have to do is get up very early and work hard. There is some social interactions but it is mostly voluntary interaction. At the airport, we never deal with customers. I only talk to the people I work with, and on days I feel especially introverted, I don't really have to talk to anybody.
I receive a good amount of respect on my job, even though it is obvious that I'm socially inept and have few friends. People respect me because I work hard and I know a lot about the operation. Most employees' would rather work with a hard-working shy guy than a lazy, outgoing comedian. My point is that, in general, people with SA can be successful at this kind of job because one's work ethic is more important than one's social aptitude.... and I know that many of you-all are both industrious and intelligent.
UPS is a unionized job, so once you've gain a good deal of seniority, your job security will be substantial. Despite the terrible economy, I feel confident that I will not get laid-off. Another benefit of being in the union is great benefits. Even though I work part-time, I still get very good benefits (medical, vacation, sick leave, 401(k), etc.).
Of course, not everything is good about the job. Some of the things I don't like are: having to wake up at 2 AM; working outside in ANY weather; the work can be repetitive and boring; not mentally challenging.
If anybody here is considering UPS, I recommend you try the air operation. The air operation is not as physically demanding and the work is more varied.