From deep to profound...
I don't know how to answer this question.
It's like asking a bird how flying has changed its life.
Hey, do remember Play Doh?
Imagine you have a small container of Play Doh. Had it since you were a kid. You've loved it ever since you first played with it and kept this one container. Let's say - just bare with me - that you've somehow managed to keep it soft and pliable all this time. Yeah, you just love this stuff.
This Play Doh is green. It's your favorite color and that's another reason you've kept it so long. The container you keep it in, well it's weird, but it has a blue top. You don't know why it has a blue top, don't recall if it was a factory error, or you lost the original green top, but it's blue and it's been blue since as long as you can remember.
One day someone - someone other than you - asks why it has that blue top.
You start to think about it and I mean really put your mind to it. It's been blue forever. As long as you can remember, right? As long as you've had this...this...green Play Doh.
Then it hits you. The Play Doh you have, the green Play Doh that you've played with for what feels like your entire life, that you love looking at on account of it being your favorite color...it was blue. It started out blue. At some point some yellow must've been added. You sort of remember that. On the edge of your recollections you recall squeezing some yellow Play Doh to make it green but for the life of you...you can't seem to remember the Play Doh being blue to start with. You can't visualize it.
You remember now that it started blue but in your mind's eye it was always green.
I've been playing tabletop, dice, pen, and paper RPGs since I was 8 years old. I am now 49. That means I've been gaming for four fifths of my life.
It's not a question of how it changed me. Changed who? Who was I before I was a gamer? I was 8. It may have molded me, taught me, provided me with an outlet, a means of making friends, but the only way I would know how it changed me would be to visit some parallel Earth where I never played.
Gaming didn't change me. Gaming is who I am.