Winter blues and a bad cold

I wonder if my concept of health is affected by the weather. Not sure what came first my winter blues or my cold. Yesterday, I went for my usual swim and a quick walk.  I was bundled but still felt the dampness. All day long I felt cold.  Today I am fighting a cold and feel miserable.  Tonight I will curl up with a hot toddy and a blanket and try to get to bed early.  I like to keep it natural...anyone have any good ideas for fighting off a winter cold and the winter blahs?