What she's saying does make sense. He knows enough about mercenaries to know that it does take a fair amount of fortitude to deal with what they deal with. If you get sick you still have a job to do, and after awhile he imagines that the small illnesses likely wouldn't even register as anything other than something to be pushed aside in order to focus on the things that are important - and he winds up nodding along with her words.

It's something he winds up regretting, though, because even that small movement is enough to make his head swim. Not badly, since he's keeping from moving anything too vigorously, but it's still enough to get him to close his eyes and press his fingers to his forehead for a few seconds.

"Ooh, my head." There's a brief grimace, but then he opens his eyes again and lets his hand fall back to rest on the table. "Sorry, you wanted to know what I was talking about?"