Real-life example:
It is finals. My java project is due in eight hours. It is not yet complete. It is midnight. I have not eaten anything all day except for some microwave popcorn, and I have consumed, in total, thirty-five diet pepsi's, ten dews, and some Nestea (we went back and checked the numbers for kicks). I have not slept in twenty hours. I should be exhausted.

I don't feel it.

I code like a maniac the entire night through. I finish one hour before the project is due. I turn it in. I go the the Palace for some chicken tenders and conversation. Halfway through said conversation, I begin laughing hysterically at a mildly funny joke, and then fall asleep.

It was a blast.