Skiing Exercising Needed

I'm lucky enough to be going away on a skiing holiday in April to Le Buet in France. I've only been skiing once before, but that was enough to teach me that this time I should do some exercise before going. Skiing really puts a lot of pressure on your leg muscles (especially when still learning), and by the end of each day I was knackered.

The problem is, I'm really busy with coursework, I hate gyms, and the thought of doing physical activity just for the sake of it (rather than, say, running for a bus) isn't something I can easily entertain.

I'm told that crouching with your back to a wall is good exercise. Maybe I'll try that. In a bit...