I sent out my first query this week. In actuality I sent out more than one, but that first one felt momentous. I reached the top of a high mountain and surveyed the valley on the other side. The valley that for most aspiring authors is littered with rejections, edits, and endless wondering. On the other side of that valley is another difficult mountain, the top of which is reached when they actually hold their book in their hand and send that first autographed copy off to the friend that told them they could actually do it. (One day you'll get that copy, Amanda!)
What do I feel like I have accomplished? Aside from actually completing a novel, of course, I have slogged through an ENORMOUS amount of research about agents, query letters, etiquette, formatting, publishers, blogs, and anything else I could think of that would help me in the publishing process. I felt like I made some significant breakthrough when I finally said, "Enough!" and hit send on my first query. Did I research enough? Polish enough? We'll find out. I did learn a lot that will make my future writing better, though.
Whether it's writing or anything else in life, at some point you just have to say, "Go!" You can research, plot, and plan forever but if you never actually move forward, you'll never actually get anywhere.