There are plenty of self-help things to do to pull oneself out of depression. To maintain good mental health though, one needs to learn how to prevent the downward spiral, if possible. (Meaning it isn't indogenous, but exogenous.)

Try reading and working through the Cognitive Distortions list at the top of the Psychotherapy forum. By changing how we think and how we react/respond to situations we can feel better about ourselves.

There is also an online self help book by drclay this is a link to the boundaries part of it http://www.psychologicalselfhelp.org.../chap8_31.html
Good wishes!