She can't tell him the truth, not really, and so instead she goes to the explanation that everyone seems most comfortable with. "I'm a soldier, of sorts. Not quite as interesting as being a scientist."

Not when you were the one out there, anyway. There's certainly plenty of excitement — hence why spy fiction is so prevalent — but unless you're of the right mindset to enjoy it, it's pure stress. Fortescue herself struggles with whether she does enjoy it.