Physical Danger
When you signed on to be an air marshal, you were probably picturing the high-octane life of a Liam Neeson character. And, yes, you might find yourself in seriously dangerous situations involving guns and krav maga.
However, those are (fortunately) few and far between. Statistically speaking, plane hijackings are extraordinarily rare. You're more likely to suffer from indigestion after eating your millionth airplane meal than you are to lose an eye while going hand-to-hand with the baddest baddie on the planet.
There's also the chance that the plane you're on could crash, though the odds of that are about 1 in 4.7 million (source).
If you want to play up the potential danger to your friends, though, we won't blow up your spot. After all, the dangerous scenarios may not crop up often, but when they do, they're about as high stakes as they come.