We've all seen it: an expedition group toiling under the weight of huge rucksacks, with all kinds of things swinging around on the outside. They have no energy for enjoying the journey - all they can think about is getting to the campsite and crashing out. But it doesn't have to be like that. When I run Mountain Leader courses I set my candidates a challenge: to pack all their kit for a three-day two-night expo into a 45 litre sack weighing no more than 10kg. Most of them are surprised, and think it isn't possible. Here's why it's a good idea, and how to do it.