I've only done that once. When I turned 17, still in a juvenile boot camp for 5 more months, I realized that I needed to change my entire way of thinking. I was psychotically emotional. I would allow my emotions to dictate every thought, belief, and action, and I knew if I continued down that path, I'd either spend life in prison, or my life would be very, very short. I decided to spend the next decade mentally training myself in the ways of what I call "logic and realism." It's similar to "realism," with differences. I basically came up with the philosophy myself. I started putting critical thought above all else, and only allowing emotion to inspire and teach. I started being objective and practical. My beliefs started requiring evidence, and my mind started actively searching for proof. Eventually, I started standing against that which I knew was wrong, and I became brutally honest after I figured out, through critical thought, that the truth is never offensive.
I'll leave it at that, as it's going to take a lot of typing to fully explain it, but that is my "worldview change." It wasn't easy, as emotions are difficult things to control when you're psychologically damaged as a child, but it's definitely not impossible, nor is it something that should take a lifetime. All it takes is proof that you need a change, and a will to be correct rather than incorrect. Ironically, I've met very, very few humans who care to be correct when found to be incorrect. Most humans are only interested in having their beliefs accepted and endorsed by others, whether those beliefs are correct or not. This is he biggest thing I stand against in humanity, as it causes delusion, which causes chaos.