They're human. Although trained to remain calm in emergency (I've fought more than one inflight fire), they still have emotions. Just as I have in other jobs, I've worked with flight attendants who were dealing with dying family members, cheating lovers, and abusive spouses.
They're sick. Although it's not a law, it's a rule of thumb that if you call in sick more than three times in six months, you'll be fired. Combine that culture with a planeload of germs and sick coworkers who should have stayed home, and you've got a vulnerable constituency.
They're tired. Despite workdays of 14 to 18 hours, their minimum layover time is only eight hours. A layover means touchdown to takeoff, so they're "resting" while briefing, while helping you board the aircraft, while finding room for your luggage in the overhead bin. Unlike other hourly employees, air crew are exempt from the Fair Labor Standards Act of 1938, which limits workdays to eight hours and workweeks to 40.
They're not getting paid. Flight attendants (and pilots) are only paid when the plane is pushed back from the gate. All of that boarding and deplaning and waiting on delays -- unpaid. I've had numerous delays of five, six, even seven hours, many of them onboard completely full aircraft. I've even served planeloads of meals on the ground before eventually canceling, which meant I was sent home without pay.
They have probably fantasized about jumping from the plane at 37,000 feet. I have. I can clearly remember pressing my face against the window at my door, looking out over a vast expanse of Nevada desert and longing for a parachute. I was on five hours sleep, had wasted the morning on a delay, the entertainment system that normally pacifies angry passengers was out, and a man screamed at me because I still hadn't brought his meal. The reason? Because I was on my knees in the aisle scooping up his son's vomit!
They love their passengers. Believe it or not, even now, most passengers are nice people and most flight attendants enjoy taking care of them. Of course I'm proud of fighting fires and assisting in medical emergencies, but my most fulfilling moments were while helping people get through trying days. I will never forget being invited to Thanksgiving dinner by several families, even after they nearly missed the holiday due to a severely delayed flight that required two aircraft swaps for mechanical problems. Passengers don't have to invite flight attendants home, but saying thank you will make their day. And for God's sake, don't hit one in the head and call him a mother fucker.