For years people smiled and told me "You're in control of the way you feel. You can always control your attitude!" I still do not believe this. Especially considering physiological chemicals your body reacts to (or produces on its own), things are not always in your control. But there is something that can help, and that will cheer and lift both you and those around you that you can control: gratitude.
Make a habit of finding something to be thankful for when you feel low. Even if it's "gee those clouds look pretty," or "I'm glad I have a full tank of gas," or "I'm so glad I can walk up stairs without help," gratitude will help, I promise you. Maybe just a little, but it will help.
Storms in life are unavoidable, and many many times it seems black clouds hover only over our own heads. Instead of trying to fight the storm, because often, nothing can make the rain stop, instead use gratitude to put the sun in your heart. You'll find your own reasons to dance and sing in the rain.