I would guess many on here have hit it right. I agree that unless you're doing a workout within the LR you should be going slower. You're kind of in an in between realm where it's not as easy as it should be. The other thing is you gotta eat something right away. Anything close to a 2hr run would always get me but drinking some Gatorade and an energy bar would fix it. I always do the majority of my morning runs without eating anything. The last thing that always made a big difference was taking a nap shortly after eating.