I have a journal, but I don't "journal"....
I only use it during bad times, its mostly used to spew the venomous filth I want to direct at my bf.
This has helped tremendously in me not having fullblown bpd *****fits, they're semi *****fits now, and are less frequent too.
Reading through the vitriol for a few days gives me time to think about what I'm thinking and feeling regarding bf. Gives me time to weigh my written reaction BEFORE bringing up whatever it is with bf. Sometimes I realize there's nothing to bring up, its purely my stuff that I was once again about to make him pay for...
I used to journal on and off in the past but always ended up ripping out the pages and then setting them on fire. Been a tradition from the age of 15, as I could never reconcile that person on paper with myself.