Tapering is Hard to Do

As a first time marathoner, this is the first time I am experiencing a lot of things, including my first real taper. Hearing other runners talk about tapering in the past, I never understood the real deal. Training tips are always telling us to follow the taper and only do what your training schedule says to do, no more! "Why," I thought, "would you ever do more?"
Yesterday, was my first long run after my tapering officially began. I had the best 12 mile run ever. In the history of running. Ok, maybe that's an over-statement but it felt so good. As I approached the end of the run, I thought briefly, "I wonder how fast I can do 13.1?" Woops. There it is. I felt great. It was cold, it was raining, I was strong, I was fast, I was consistent. I wanted to do more. I stopped myself. I ran just slightly more than 12 miles and then reminded myself that I am so close, yet if I injure myself or over-train, I will be so far away.
Less than 2 weeks. There is so much to do, including successfully following my tapering training schedule.