Depression is nothing new to a lot of folks, it’s the method you employ to work your way out of it that is different for each individual. While not prone to depression myself, I do find myself ruminating about the past a lot, living with regrets, etc.
The one thing I’ve found helpful is to be mindful of the Present, and to treat everything as if it’s the first time you’ve experienced it. I recommend the book “Only Don’t Know” by Seung Sahn. This book will literally transform your outlook on life and how you interact with it.