I'm also in the boat of "Telling stories keeps me living". Maybe it's a good thing I'm a bit of a control freak, because the idea of dying and having someone else take over my story sounds awful! ;d So even in the worst of times, I know I have to stick around so long as I have a story to tell.
It especially motivates me when people express that they relate to the comic or it brought them happiness; if I can make at least one person feel a little less alone, then that's worth something.
Also I've spent so much time developing these various characters and worlds, it feels like a waste to keep them all trapped in my head. Making comics helps me free up all that brain space by putting that stuff out into the real world and letting other people look at it. D: