The next morning, with a clearer head than I'd had in a week, I began to rationalize reasons to feel good about getting sick. First of all, I told myself, I exercised my immune system. By calling my white blood cells to action, I have ensured that my immune system will be at peak performance for the 14-hour plane ride to Tokyo. If I'm going to be trapped in a giant flying tin can, inhaling the recirculated, germ-infested exhalations of a hundred other people, those cells better be buff. And as I step onto foreign land and am introduced to germs with unfamiliar accents, my antibodies -- toned, agile, and alert -- will be ready to defend me. Come to think of it, getting a cold right before this trip is the best thing I could have done for myself. It's too bad David's system is so weak. When he gets sick abroad, I'll think, that's because you didn't plan as well as I did .