If you are feeling low and wondering "Is this all I have to look forward to?" - Don't worry it is the winter blues grabbing hold of that mind....the lack of sunshine is a huge factor on motivation.
But it is also a chance to think about what is important to you. Often we are trying to define ourselves or measure our happiness from what we do or achieve......it is not wrong, but don't forget to think about measuring your day to day life against who you are.
Often depression hits because you are not doing something that is core to your values...you may be achieving a lot and yet it doesn't seem to make you happy. If that is the case take a few minutes to think about your values, who you are and make sure that your day to day life is fulfilling these needs. No money will ever compensate for you working or living against your desires or values.