This has been the story for me in 2009 so far. In my third year of serious riding I have attempted things I didn't "think" I could do and found out that I'm only limited by that very thought. We have a hill in our area known as Lamb's Canyon. The section I did today shows 563' of climb in 3.8 miles. The entire hill is 1350' of gain in 5.6 miles, which I will do next time, but today I decided to just tackle the first section as the beginning of my 34 mile ride. As in the century I did a few weeks ago, this was not near as difficult as I imagined and I am rapidly getting to the point of looking for things to challenge me further.
The bottom line is we are truly limited by our thoughts and if we push them aside we can accomplish much more than we think we can. Too bad I had to learn some of these things so late in life!