All the pain and suffering when you're sick. Waking up a dozen times in the middle of the night to painfully cough. Dizziness, lack of energy, stomach cramping...
But what really gets me is that I'm doing it to myself! Me in the physical-me sense, not the conscious-me sense. The unhappiness is all just a side effect of making your body a miserable place for the germs to live, too.
I guess we have to evolve to hate being sick, because it is dangerous, and the more we can learn to avoid sickness the better. And I guess learning to avoid sickness has been important - e.g. the invention of washing your hands.
None of this philosophy makes my throat hurt any less though ;-)