Why do dogs pace?

This morning I wake up, and like every morning, my dog comes to the side of the bed and stares at me.  She walks to the door, comes back to the bed, goes back to the door and then finally sits next to the bed.  Two seconds later, she repeats the same process.  I always wondered why dogs pace back and forth so I did what I always do when I want to look something up – I "Googled" it.  Dogs pace because they have a ton of energy and don’t know what to do with it.  That energy can be reduced by giving your dog plenty of exercise.  The only thing my dog wants to do in the morning is go outside, do the deed and  then come back in to eat.  She usually doesn’t get her exercise until the evening, when it’s somewhat cooler outside.