My own (non-scientific) opinion is related to this. In my experience, resistance to negative emotions is a much more crucial ingredient to happiness. As I’ve been gradually maturing during my life, I think the biggest improvement is that I’m quite emotionally stable. Small and unimportant things don’t bother me much at all, which really helps when it comes to leading a happy and fulfilling life. Especially as negative experiences are supposed to have a greater impact that positive ones.