I hate people who have no sense of responsibility. I hate those who say they want this or that but never do anything about it. I hate it most when people promise you something and then they don't it for the silliest of reasons, like say, a headache.
Seriously, who doesn't go to work for a simple headache? This is why paracetamol or mefenamic was invented. If everyone in the world doesn't go to work simply because their head aches, nothing would be done.