My inspiration to ride is that I know I am helping make the world a better place...even if it is .0000000000000000000000000001 percent difference in how the world turns it is still a difference.
I began commuting by bike 6 months ago, I have missed one day in six months of commuting. It has been getting pretty cold and wet, especially this last week, and I find that I enjoy riding in the cold just as much if not more than riding in the warm weather. As far as the rain goes, I actually find it kind of refreshing when you are properly dressed, although I don't think I'd recommend riding in a winter downpour.