It's never a life that gets me down as whatever happens is a consequence of my actions according to my beliefs. Which make it harder to deal with the mood as I cannot blame someone else ;)
So when I'm down I sometime simply let myself to be like that and slowly regenerate.
When it stays for too long I often face the things that I'm not happy about and once I get them analized and put plan in place to change it for the better, my spirit lifts up.
Sometimes when I'm low because of feeling overwhelmed with all the things I 'have to' do, I take a break - either by enjoying outdoor and beauty of the nature or by having a me time reading, doing jigsaws or anything relaxing.