I'm so tired...

Why am I so exhausted lately? I don't know if my body isn't fully adjusted to working (although it has been over a month since school started, how long can it take?!) or what but I am so tired lately. I can't even use winter as an excuse because it isn't even cold yet. I'm supposed to be running a half marathon, 10K, and 5K in the month of October and I'm slightly panicky that I won't make it. Hopefully things will begin to ease up and I'll start feeling more rested. Something has to give, right?