I confront the cause.
What do you do when you have something on your mind bothering you?
I pray. Then I try to think of the worst-case scenario and realize it's not the end of the world. Once I do that, I can usually begin planning a logical solution (a lifestyle change, an apology, a doctor appointment, etc.)
It depends on what it is. If it is someone else's actions, I will either find a way to talk to them about it, or I will decide if they are even worth keeping around. If it is something that I can control, I find a way to deal with it.