I wouldn't think of depression as a passing emotion though. This is more about acute emotions like anger. Depression seems it often has a lot more to do with your actual physical brain chemistry which we cannot directly control.
Edit: Actually thinking about it more, regular emotions also must have to do with our brain chemistry as well. So we can affect our brain chemistry on some level.
Edit 2: Or maybe we cant really control any of it and are purely along for the ride. Who knows.