In a way @adsactly that is one question that you can only answer for yourself as we are all different, our live experiences are different. I don't know what has happen in your life to bring you to this question. Depression can sometimes be triggered by some event in our lives, something we might not have dealt with. Identifying that can be easy or hard. But this is something that we can do, we live in a world where alot of people are made to feel disempowered, we need to feel strong enough in ourselves to heal ourselves.
There are alot of really good responses to your question already, which can help, vit D definitely helps as does your diet, it's worth seeing if you have any mineral deficiencies . Selenium is a big one, as it has huge effect on our mood. These things will go hand in hand with you feeling more able to work through your depression. What factors externally and internally affect you the most. Identify them so that you can prevent yourself getting into a downward spiral, which can be difficult to get out of.
What worries me about antidepressants is that there are so many and are prescribed too readily, there is big money made from them, Doctors make alot of profit when they prescribe also. I would love to see people move away from using medication to help with their mental health. I hope you feel better soon.
Getting to know yourself and the depression triggers, can definitely be diet - caffeine is a big one for me. Will definitely look more into supplements and vitamin deficiencies. Yes everyone is different, but the emotions we go through are the same, we are all human.