There are spells of “winter blues” and then there is true (non-seasonal) sadness. Melancholics may take note of this article from the Opus Dei newsletter

http://opusdei.us/en-us/article/5-remedies-against-sadness/

in which Carlo de Marchi, vicar of Opus Dei for Central-South Italy, outlines five surprisingly down-to-earth remedies against sadness from St. Thomas Aquinas.