In total I must have gotten 12 hours of sleep over the weekend due to family being in from out of town, but I still got up and worked a full day without an ounce of tiredness. It wasn't until around 10:30pm that my body demanded sleep.
I also noted that I have similar creative productivity at 6am as I used to at 1am when I was on night-owl hours. So I now use my extra morning time to get writing done that I find hard to get to later in the day.
Try the olympics lifts: power cleans and snatches and squat cleans and snatches. Or their components: deadlifts, front squats, presses. Or back squats and thrusters. Do a bunch of those in rapid succession and your whole body will be much more tired than doing a 5k run, guaranteed.
Check out Mark Rippetoe's "Starting Strength" [1] for more info. Great program for anyone new to weightlifting.