Not 6 weeks, but I used to spend the month of March in Hokkaido. 30 day stay, generally skied 28'ish days. One year, day 18'ish, I just ran out of gas at lunch, and around day 24 the areas closed because of a wind event, so I guess I made it 28.5 days out of 30. Felt pretty good the whole time , and was on telemark gear for the duration for both lift served and touring. I ate well. Very well. Drank some, not too much, but enough. Also had a hot bath every morning and evening. The bath thing was key IMHO. Previous to March, I'd typically ski 3 days a week from about mid December on, so had pretty good base ski fitness, and did a good deal of gym work, road cycling, and some squash in the off season.