what activities can i do to lift my mood?

Join you local Habitat for Humanity and help build a home for someone who wouldn't have one but for you. You will learn while doing this and meet some great people. Nothing lifts your mood more than helping others.

Exercise and bright light improve mood. Exercise is self explanatory. Bright light varies with the season. People who are more susceptible to the change in light are said to have SAD, Seasonal Affective Disorder. You can compensate by putting brighter lights in the bathroom where you wash up in the morning. Thirty minutes of bright light in the morning can do wonders. Also try to get out during daylight for a walk. Perhaps you can add extra light to your work space.

I agree with helping others answers. It is experienced helping others take you out of your mind and obsession as well.