Having gotten myself out of a startup-induced depression I feel for you. Getting out of a depression is never easy, you simply cannot spot the right paths to take you out of there while in it. I can only give you some advice which helped me greatly:
1) Get opinionated. Try to form opinions about everything around you. What do you like or dislike about that lamp post? Which one is your favorite fruit and why? These type of silly exercises is a good way of building up an image of what you want in life. When you know what you want, you can figure out how to achieve it. Being passive is horribly depression-inducing.
2) Participate in life coaching, preferably both individually and in groups. This helped me getting a more objective view of what type of individual I am, how other people see me. But also what other type of personalities there are and how they interact. Knowing all this has helped me view disagreements and conflicts in a new light. I don't have to take myself and everything around me so seriously, since I can see more clearly why things happen as they do.