Clients with depression has a certain neural brain path way that connects stimuli to depressed emotions. Clients have greater tenancies to these emotions. There are 2 big theories out there: creating/exercising positive pathways or stopping the neural pathways medically. Both can be used at the same time.

I recommend talking to someone so you can teach yourself how to deal with the relationship with yourself and others.

Here's a counseling/consulting place:
http://www.yogasha.com/

You're reaching out on this board, which is a definite positive step.