First kilo I did, I barely made it to the finish line I was so spent. I collapsed on an open patch of grass and was only able to get one foot unclipped. I was like a fish out of water, gasping for air and flopping on the ground trying to remove my helmet and unclip.
I vaguely remember someone coming over, leaning over me, blocking the sun, and taking a look at me as I thought I was dying and said, "Yeah, you did it right."