This morning I decided to cut down on my running mileage by getting on the recumbent bike at the gym first. I did 30 minutes on bike (5.15 miles), and right about that time a treadmill opened up, and I took that as a sign. Planning just to go a mile or so, I started to think about the big difference in calorie burning between the recumbent bike and the treadmill, and I just kept going on the treadmill. My legs had felt tired when I got up this morning (although I went to bed early and had a good night's sleep), so I didn't feel like the Energizer Bunny at all, but I was able to keep going for 30 minutes and 2.34 miles (still under a 13 min/mile pace, which has been a goal for weekday runs lately).
My legs are still feeling tired, and I've been planning a long run tomorrow, so we'll see how that goes. I'll make sure I drink plenty of water today and will try to get to bed early again tonight.