Gym. Boring, but it has to be done.

Cycle Trainer. Less boring with the right DVDs and I try to do at least 10 hours a week.

Snow shoes! That's a new one, but 1/2 in deep snow with them makes 1 hour at the gym feel like nothing. I can't go too far yet, but it's fun and turns into something of a 'family activity'. I break new ground for my husband creeping behind me on cross country skis while the dog bounds around through the snow up to his chest or shoulder. When I need to take a break to let the lactic acid leave my leg muscles, he and the dog skijor back and forth along the new path. When we get home, we're all happily exhausted.