Recently, I've been working on a large project that required learning and collating lots of new data. It's been a big challenge with several unexpected turns, so it has been dominating my thoughts for weeks now.
Today, it all came together and pulled together into a demonstrable project, which was amazing; I was elated and eager to show everyone around me.
30 minutes later and I'm resting with my head in my hands because I am abruptly so tired. People asked if something was wrong and nothing could be further from the truth, yet I am utterly exhausted.
Is there a word or saying for this state, or even a better way to describe it than the above? For example, "Nothing's wrong, it's just [exhaustion after success on a long and tough project]."