I'm assuming you live in a very wintry place right? You ever thought of taking up snow sports? I XC ski (both skate and classic) and snowshoe, but really could only do those sports on the weekends. Gave up snowboarding after getting sick of the crowds at my local hill. Last year I did a 6 week ski conditioning class that was held at my gym twice a week for 1.5 hours. That was a kickass workout. I wanted to do it again this year, but after I found out who was teaching it I said hell no (cuz I hate the guy...last year our instructor was HOT!!!).
I lift on a weekly basis throughout the year usually 2x/week.
My old tolerance for riding in the cold is low/mid 30s and when it's dry. But after yesterday, I think I'm able to reasonably tolerate the 20s just as long as the wind ain't blowing and as long as it ain't rain/sleeting/snowing on me. But even then it's only for an hour or so at night and only one to two times a week. If I ain't riding, then I'm running outside.
I HATE HATE HATE doing any cardio work inside, but sometimes that is the only option and it's an aerobics class or Spinning class or run on the indoor track at my gym or hit a couple of the cardio machines. I try my damn best to avoid doing any of that though if I can help it.
Oh yeah....my Yeti is mainly hibernating this winter in my equipment room. I got my second singlespeed built up last month by fellow 575 owner flipinidaho. I began SS'ing earlier this year and loved it. This new SS is more climbing friendly than my first SS. I figure if I can SS from now till late winter/early spring...I will have built up alot of leg strength by the time I re-mount the Yeti.