How do you get through your bad days?

I had an important phone call this morning that made me anxious (I hate phone calls !!) and it just took all my energy and left me feeling down the rest of the day. The weather has also been dark, gloomy, and too cold every day which is definitely affecting my mood. I took a nap and just felt like crap. It's hard to get anything done or leave the house on days like these.