DD2(13)gets seriously cold in her ski/snowboard boots. We've tried those little packs (Hot Coal?) which warm up but they tend to turn into an uncomfortable, hot lump which burns heats only one tiny part of her foot. Can anyone recommend some heated insoles? She's a keen skier and snowboarder but is already psyching herself up for an uncomfortable, painful, cold holiday - and I'd be quite pleased if we didn't have the usual whingeing, whining and complaining. I have, of course, Googled, but "personal" recommendations are usually the best, aren't they? 