Power
Unless you're, like, super into felonies, you're earning pretty much zero official power by wearing that little blue hat with the eagle on it.
If there's any power to be had in this profession at all, it's in what you don't do.
Don't sort the Santa letters into the "return to sender" pile or you'll create an Amazonian river of tears from suburbia to the gates of the post office. Don't forget to deliver the mail, because you might end up keeping a life-saving prescription from someone who needs it. And if you are late opening the office, Madison won't be able to send her rent check in before class...and she'll probably be kicked out onto the street. Are you happy now? Huh? Are you?
Regardless of email proliferation, text messages, and automatic bill pay, the USPS still provides a vital service. Maybe not quite as vital as it once was—shhh, not so loud...it'll hear you—but still pretty vital. So, your power is to not screw that up.