Highs and Lows

Isn't it weird how you'll be on a total high, on top of the world, a superman? And then as soon as you stop doing whatever your doing, you just crash. Down and down and down you go... This has happened to me in the last few weeks a lot. For instance, I was taking an academic competition test (I placed 4th, by the way) and I left school and just went home and as soon as I stopped moving, I just started to crash. Just now, I was working in my school library, helping out with some inventory stuff and crosschecking facts, and then I switched into my next class and down I went... I'm fed up with this tired feeling...