Why is a nap so difficult?

Nap time is a mom's favorite time of day. For anywhere between one and three hours, it's MY time. The daily nap routine goes something like this. Milk, some time in the rocking chair and then into the crib fast asleep. Today is one of those occasions where before I can creep out the door of his room, he awakens and begins to scream. My heart drops. The fate of my afternoon becomes uncertain. Will he EVER sleep now? Will I be destined to cater to the whim of a grumpy, tired toddler until bedtime? Sometimes there are tears...from me that is. Sometimes it's no big deal. Sometimes it just means I get to go to Target at 2pm instead of 4pm. But today, I'm pissed. I can hear him in the crib making little noises, the kind of noises that indicate he won't be falling alseep any time soon. Which means I'm in for a hellacious afternoon.