I think I'm dying.
It's the only explanation.
My symptoms: euphoria, delirium, child-like excitement.
This is the state I find myself in.
My characters are talking to me. Backstory is unfolding. Action is fully engaged. I am giddy like a crazy person.
The end of the first draft is within sight. It's plotted and ready for fleshing out.
Excuse me while I type away madly...