Life’s too short to be bummed out all the time

A few times when talking to J I’ve been describing a positive character trait and noted that I take no credit for having it, I’ve just always been that way. I often wonder if super-positive people were always that way, and say such things as an excuse, or if they used to live in bummer-town and somehow grew/talked their way out of it. I’d love to hear the latter story.