I think that if your depression has an important biological component, triggers may not be that important. You may have "waves of depression" regardless past or current events. Of course, the biological components of your depression do not operate in isolation, they interact with other factors.
I think that the genesis of your depression (a traumatic event, family patterns, etc) is not as important as the way your depression works actually.
In my case, medication plays a fundamental role in the beginning of the recovery. It helps me to lift me up. Then, there are other things that help me better, like cognitive tools and mindfulness.