Glory
Some agents make the work itself out to be glorious. After all, you're working to protect the hundreds of millions of people living just behind you. People generally recognize border agents as respectable, trustworthy people, which means you'll get a lot of free pizza and ice cream from community organizations. Lots of your work will happen outdoors, and nothing beats a desert sunset or a snow-capped peak in the distance.
There are also the people you help directly. You're the first person a legal immigrant sees when they are finally allowed access into the United States. You're there as much to help those who have gone through the process of legal entry as much as you are to catch those trying to sneak across. Then there are those who are trafficking victims who will be thrilled when you show up to take down their captors.
By the way, this doesn't mean you treat any one of them any less humanely—you just point them in the proper direction (north, south, or to a hospital close by).
It's important to be able to savor the glorious moments in your job, because the work can wear on you. Which actually leads us to our next topic.