Constantly Lying - Is It Related to My Mental Health?

I used to have this same problem. I have c-ptsd and bpd as well. It took me over 10 years to train myself out of the "habit" of lying about little things. I kind of always viewed it, like the other commenter said, as a mask to fit in. The little lies kept people from diving into the real me and finding out how messed up I was. Casually lying about the surface stuff to seem "normal" prevented anyone from trying to figure out anything deeper. I never really noticed that I was doing it until someone brought to light a contradiction of that day's lies with those from a previous conversation.

I struggle with this as well! I lie over everything, like things I've seen on my way home, stuff the kids did that day, and it's always small things that don't even matter. I try to remind myself not to do it and then like you said I catch myself in mid-conversation lying up a storm. I also have C-PTSD and BPD. I don't know what it stems from, I always figured it was because I never was accepted or "fit in" growing up so I learned to mask others and lie to be noticed and accepted.