I can pin the most recent leap on one particular moment. I've been stuck in the mud for a while, taking the same type of shots over and over, and I realized that a huge part of it was that I'm just too bloody shy for my own good.
I was in The Free State of Christiania here in Copenhagen, and I was sitting in a bench by the waters edge taking a break. I glanced up, and saw a man who looked like he had just walked out of Auschwitz. His face was incredibly shocking, and he wore a sweater with a deep hood, presumeably to hide his face. He walked past me, and all I could think is "I want to take a photo of that man."
I kept sitting on the bench, cursing myself for 100 types of coward, and finally I told myself "If you want the damn shot, you'd better get up off your ass and go get it!" I got up and walked as fast as I could to catch up with him. I finally caught up with him (he walked really fast). I took a deep breath and said "Excuse me, but I am an american photographer, and I would very much like to take your photo if it's ok (in Danish)".
He said "what?" I repeated myself, and he said "NO!" very loudly and hurried off. On the walk back into Christiania, I realized that I was terrified up until the moment I actually began to speak to him. At that point, I had committed myself and was working. I realized that you'll never get the shots you want if you let them just walk past. Have the courage to take the shots, because the worst that can happen is someone will say "No."
So, in an odd way I learned the most from a photo I chose not to take. While I wish that he said yes, I could understand his not wanting his photo taken and respected it. I haven't completely gotten over my fear of asking people, but it's getting easier every time.