Or has your mental health always existed, simply stayed the same or improved?
I think I was always a bit more sensitive and anxious than other kids, a "scaredy cat", afraid to climb the rope in PE, afraid to jump off things, afraid of trying to climb anything high and needing help because I was simply crap at it, afraid of dogs barking, afraid of people's masks on Halloween...but this tendency to be afraid wasn't debilitating and my childhood was mostly normal as far as I can tell.
My anxiety has actually gotten worse with age, particularly social anxiety and agoraphobia. Agoraphobia itself feels like I've reverted back to childhood in a sense as I feel small and overwhelmed by the outside world but can largely cope now with the help of medication and CBT.