The way I keep from falling into depression is to remind myself it is a thinking spiral, you think one bad/sad thing, that goes to the next etc etc. I don't let myself go to the first starting thoughts, tell myself, that for me anyway, it is self indulgence, self absorbed, waste of time. After being on many antidepressants for over 25 years off and on, in addition to other types of therapies etc, it was, for me, cognitive therapy that clicked. But I was one who an antidepressant would only work well for 2 to 3 years, then crash. Last crash was a mess for months. I was diagnosed, at least this last time with "double depression", dysthymia with bouts of severe depression. Years earlier it had been diagnosed as PTSD, and other things. I believe we have to do as much for ourselves as we can WHEN WE CAN. I personally don't believe it is a person, a job, a hobby, a thing that "fixes" us, these things can help, but they are not to be depended on. I know I don't want to be the person responsible for anothers mental health. While getting a grip, I found some things that held meaning for me that I hopefully will have for the rest of my life, in some way.
Best of luck, it's good to read about others sometimes, but like the say "If you meet the Buddha on the road, kill him", meaning we each have to find our own answers, and anyone claiming to have YOUR answers can be dangerous.