I've had two moments of hubris, where in my defiance of the gods I discovered my potential.
The first was over 10 years ago, when I still a beginner web developer. I had just managed to get a mechanized slider mixer to interface with my computer using WebMIDI, and was able to send commands to make the sliders move all over the place. It was then I realized that I could ben computers to my will. Anything was possible if I understood the problem well enough.
The second wasn't long after that when I watched contestants on the Great British Bake Off make croissants. I've always thought croissants to be far outside the realm of my abilities, and they were sure to point out every challenge and difficulty as they made them. But when I watched the actual process, I realized — this isn't that hard. Sure, it's time consuming and does require some skill, but even a shoddy croissant is probably good enough. And sure enough, when I found a recipe and tried making them myself, they were delicious. Once again, I unlocked something in my brain allowing me to bake literally anything if I really wanted to — neither pastry or bread nor cake could thwart me.
There's something about trying to do something in spite of thinking it won't work.