There are many natural remedies for bouts of depression. I would suggest that you get a chemical test, can't remember the name, to see if it is biological or psychological.
If you're levels are mostly normal or "within range", then try the following...
1. Remember that men go through stages as they create, work, then reach goals. Once certain goals have been obtained, there may be a temporary setback in psychological health while you aimlessly search for a new target. This is totally normal and may last days or weeks. Once you get into months, you should go to number 2...
2. Do you have a purpose in life right now? Some sort of goal you are moving towards? I think most depression is a result of men (and women) not having a real direction in life. Another possibility is that your purpose is not something you are really passionate about
3. Physical and strenuous exercise helps release some of those neurotransmitters that are incredibly healthy for your mental health. Some would argue that exercise helps your mind more than your body.
4. Diet plays an enormous role in your mental health. The massive amount of sugar in our diets causes significant sugar spikes, which keeps your mind in constant disarray. Try cutting out all carbs and see if that helps.