I have cycled in temperatures down to -40C ... just commutes at those temperatures, but this is the story of my coldest century: http://www.machka.net/brevet/Coldest_Century.htm

So don't tell me you can not ride in winter!

As well as cycling relatively regularly through both Canadian and Australia winters, I also ride my trainer, join spinning classes, cross country ski, snowshoe, lift weights, take yoga classes, and do lots and lots of walking.