I've always known that food is a morale booster. Anyone who's spent an ungodly number of hours on a freezing cold set getting photographed over and over and over will appreciate a cup of hot soup. Even some weak, disgusting coffee would be welcome right then. And really good food—well…

It's not just eating good food that's a morale booster. Cooking has always cheered me up and made me feel better, even when I wasn't in the mood to eat anything myself. Even now… what happens when friends come to visit? They bring food, of course. And we all enjoy eating it, even if it means spending a few extra hours in the gym the following week.

But did I ever think about nothing but food for a whole day? Maybe when we were all on diets and daydreaming about chilli sauce and fried chicken and strawberry ice cream. And survival class is very different from that.

I love food. I love to cook. But some of the guys in the troop know a lot more about food than I do. I've never looked as food as a survival tool. Not the way I do after today's lessons. Evaluating food not by taste or want, but nutritional value and energy content isn't really that enjoyable. Calories, trace minerals, fats, vitamins… working out how much each food offers, how much effort it takes to find and prepare it and how long you can survive with what you have. It's surprisingly scary stuff.

Food's always been a comfort for me and I'm just a tad worried that I'm going to lose that the more I learn. But then, I had no idea that worrying and anxiety burn calories, that you can literally worry yourself thin. It explains so much, though…