I ride year round and always have done. The bike is my only form of transport aside so I never really considered locking it up for the winter. But I love being outside in all kinds of weather all year. That's the best part of living in a place that has seasons! You get to go out and enjoy them.
Summer: warm sunshine on your skin and a warm breeze through your hair. Fall: crisp air and fantastic colours on the trees.
Winter: crispy cold fresh air and if you're lucky lots of white snow to brighten things up.
Spring: beautiful wildflowers popping up everywhere and the wonderful feeling of the first warm sunshine.

Just dress for the weather. If it's cold, layer up. I've found that the best solution is to wear many thinner layers rather than one thick layer. You will warm up as you get going and will want to shed a layer or two. If you stop along the way for a break, bring a dry shirt to change into so you're not wet which will cool you down very fast. And something windproof is generally a good idea in winter.