Well first off, let's make the clear distinction between colloquial 'depression'--you know, the existential shit or the ritual of bad lifestyle habits--and what is called 'clinical depression'--where a person's neurochemical baseline is flawed from the get-go (i.e. where there is a seratonin or dopamine deficiency or whatever confluence of factors it might be).
You can't 'get over' clinical depression, in the same way you can't 'get over' sickle-cell anemia.
I agree that bipolar's symptoms can be mitigated, but it's not a matter of some triumph of the spirit. You can learn to avoid and cope with stress, you can avoid aggravating factors like caffeine and alcohol and marijuana, you can maintain a healthy diet and sleep schedule, you can stay active and social and productive, but you simply can't 'get over' bipolar with willpower or emotional fortitude or whatever.
I still think that a big part of overcoming the illness is to take action against it; I referenced "get over it" because it's a common argument against depression that people have that is terribly oversimplified and just plain wrong, however I think that there is a certain part of conquering depression that is consciously acting differently to how you feel. This is not an easy task and it's a process that can take years, whereas "get over it" implies that it is just a simple problem that can be gotten over in a day or two if just ignored. I completely understand the difference between clinical depression and typical sadness, as I have experienced it myself many times.